ICND1 Flashcards
How does a switch differ from a hub?
A. A switch does not induce any latency into the frame transfer time.
B. A switch tracks MAC addresses of directly-connected devices.
C. A switch operates at a lower, more efficient layer of the OSI model.
D. A switch decreases the number of broadcast domains.
E. A switch decreases the number of collision domains.
B. A switch tracks MAC addresses of directly-connected devices.
Explanation:
Some of the features and functions of a switch include:
A switch is essentially a fast, multi-port bridge, which can contain dozens of ports. Rather than creating
two collision domains, each port creates its own collision domain. In a network of twenty nodes, twenty
collision domains exist if each node is plugged into its own switch port. If an uplink port is included, one
switch creates twenty-one single-node collision domains. A switch dynamically builds and maintains a
Content-Addressable Memory (CAM) table, holding all of the necessary MAC information for each port.
What must occur before a workstation can exchange HTTP packets with a web server?
A. A UDP connection must be established between the workstation and its default gateway.
B. A UDP connection must be established between the workstation and the web server.
C. A TCP connection must be established between the workstation and its default gateway.
D. A TCP connection must be established between the workstation and the web server.
E. An ICMP connection must be established between the workstation and its default gateway.
F. An ICMP connection must be established between the workstation and the web server.
D. A TCP connection must be established between the workstation and the web server.
Explanation:
HTTP uses TCP port 80.
3.How does TCP differ from UDP? (Choose two.)
A. TCP provides best effort delivery.
B. TCP provides synchronized communication.
C. TCP segments are essentially datagrams.
D. TCP provides sequence numbering of packets.
E. TCP uses broadcast delivery.
B. TCP provides synchronized communication.
D. TCP provides sequence numbering of packets.
Explanation:
TCP differs from UDP in the following ways: TCP provides best effort delivery.
TCP provides synchronized communication. TCP segments are essentially datagrams. TCP provides
sequence numbering of packets. TCP uses broadcast delivery.
4.A workstation has just resolved a browser URL to the IP address of a server.
What protocol will the workstation now use to determine the destination MAC address to be placed into
frames directed toward the server?
A. HTTP B. DNS C. DHCP D. RARP E. ARP
E. ARP
Host A is sending a packet to Host B for the first time.
What destination MAC address will Host A use in the ARP request?
A. 192.168.0.1 B. 172.16.0.50 C. 00-17-94-61-18-b0 D. 00-19-d3-2d-c3-b2 E. ff-ff-ff-ff-ff-ff F. 255.255.255.255
E. ff-ff-ff-ff-ff-ff
Explanation:
For the initial communication, Host A will send a broadcast ARP (all F’s) to determine the correct address
to use to reach the destination.
The network manager has requested a 300-workstation expansion of the network.
The workstations are to be installed in a single broadcast domain, but each workstation must have its own
collision domain. The expansion is to be as cost-effective as possible while still meeting the requirements.
Which three items will adequately fulfill the request? (Choose three).
A. one IP subnet with a mask of 255.255.254.0
B. two IP subnets with a mask of 255.255.255.0
C. seven 48-port hubs
D. seven 48-port switches
E. one router interface
F. seven router interfaces
A. one IP subnet with a mask of 255.255.254.0
D. seven 48-port switches
E. one router interface
Explanation:
A 255.255.254.0 subnet can absorb 510 hosts being a 23 bit mask and also 7*48 port switches can handle this
much hosts and router interface is required to be minimum to avoid unnecessary wastage hence the answers.
What are two common TCP applications? (Choose two.)
A. TFTP B. SMTP C. SNMP D. FTP E. DNS
B. SMTP
D. FTP
Explanation:
SMTP uses TCP port 25, while FTP uses TCP ports 20 and 21.
Which method does a connected trunk port use to tag VLAN traffic?
A. IEEE 802 1w
B. IEEE 802 1D
C. IEEE 802 1Q
D. IEEE 802 1p
C. IEEE 802 1Q
Explanation:
IEEE 802.1Q is the networking standard that supports virtual LANs (VLANs) on an Ethernet network.
When a frame enters the VLAN-aware portion of the network (a trunk link, for example), a VLAN ID tag is
added to represent the VLAN membership of that frame. The picture below shows how VLAN tag is
added and removed while going through the network.
Which two statements describe the operation of the CSMA/CD access method? (Choose two.)
A. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.
B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
C. The use of hubs to enlarge the size of collision domains is one way to improve the operation of the
CSMA/CD access method.
D. After a collision, the station that detected the collision has first priority to resend the lost data.
E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired,
all stations have equal priority to transmit data.
F. After a collision, all stations involved run an identical backoff algorithm and then synchronize with each
other prior to transmitting data.
B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired,
all stations have equal priority to transmit data.
Explanation:
Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the
network medium. CSMA/CD was created to overcome the problem of those collisions that occur when
packets are transmitted simultaneously from different nodes. And trust me, good collision management is
crucial, because when a node transmits in a CSMA/CD network, all the other nodes on the network
receive and examine that transmission. Only bridges and routers can effectively prevent a transmission from propagating throughout the entire network! So, how does the CSMA/CD protocol work? Like this:
when a host wants to transmit over the network, it first checks for the presence of a digital signal on the
wire. If all is clear (no other host is transmitting), the host will then proceed with its transmission. But it
doesn’t stop there. The transmitting host constantly monitors the wire to make sure no other hosts begin
transmitting. If the host detects another signal on the wire, it sends out an extended jam signal that
causes all nodes on the segment to stop sending data (think, busy signal). The nodes respond to that jam
signal by waiting a while before attempting to transmit again. Backoff algorithms determine when the
colliding stations can retransmit. If collisions keep occurring after 15 tries, the nodes attempting to
transmit will then time out.
Which two options will help to solve the problem of a network that is suffering a broadcast storm?
(Choose two.)
A. a bridge B. a router C. a hub D. a Layer 3 switch E. an access point
B. a router
D. a Layer 3 switch
Explanation:
Routers and layer 3 switches will not propagate broadcast traffic beyond the local segment, so the use of
these devices is the best method for eliminating broadcast storms.
What does a host on an Ethernet network do when it is creating a frame and it does not have the
destination address?
A. drops the frame
B. sends out a Layer 3 broadcast message
C. sends a message to the router requesting the address
D. sends out an ARP request with the destination IP address
D. sends out an ARP request with the destination IP address
Explanation:
Understanding this concept is prime for understanding that when switch receives the data frame from the
host not having the MAC address already in the MAC table, it will add the MAC address to the source port
on the MAC address table and sends the data frame. If the switch already has the MAC address in it’s
table for the destination, it will forward the frame directly to the destination port. If it was not already in it’s MAC table, then they frame would have been flooded out all ports except for the port that it came from.
A switch has 48 ports and 4 VLANs.
How many collision and broadcast domains exist on the switch (collision, broadcast)?
A. 4, 48 B. 48, 4 C. 48, 1 D. 1, 48 E. 4, 1
B. 48, 4
Explanation:
A switch uses a separate collision domain for each port, and each VLAN is a separate broadcast domain.
Which address type does a switch use to make selective forwarding decisions?
A. source IP address B. destination IP address C. source and destination IP address D. source MAC address E. destination MAC address
E. destination MAC address
Explanation:
Switches analyze the destination MAC to make its forwarding decision since it is a layer 2 device. Routers
use the destination IP address to make forwarding decisions.
On a Cisco switch, which protocol determines if an attached VoIP phone is from Cisco or from another
vendor?
A. RTP
B. TCP
C. CDP
D. UDP
C. CDP
Explanation:
The Cisco Unified IP Phone uses CDP to communicate information such as auxiliary VLAN ID, per port
power management details, and Quality of Service (QoS) configuration information with the Cisco
Catalyst switch.
A switch receives a frame on one of its ports. There is no entry in the MAC address table for the
destination MAC address.
What will the switch do with the frame?
A. drop the frame
B. forward it out of all ports except the one that received it
C. forward it out of all ports
D. store it until it learns the correct port
B. forward it out of all ports except the one that received it
Explanation:
Understanding this concept is prime for understanding that when switch receives the data frame from the
host not having the MAC address already in the MAC table, it will add the MAC address to the source port
on the MAC address table and sends the data frame. If the switch already has the MAC address in it’s
table for the destination, it will forward the frame directly to the destination port. If it was not already in it’s MAC table, then they frame would have been flooded out all ports except for the port that it came from.
At which layer of the OSI model does the protocol that provides the information that is displayed by the
show cdp neighbors command operate?
A. application B. transport C. network D. physical E. data link
E. data link
Explanation:
CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco- manufactured
devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices.With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices running lower-layer, transparent protocols.
Which two characteristics apply to Layer 2 switches? (Choose two.)
A. increases the number of collision domains
B. decreases the number of collision domains
C. implements VLAN
D. decreases the number of broadcast domains
E. uses the IP address to make decisions for forwarding data packets
A. increases the number of collision domains
C. implements VLAN
Explanation:
Layer 2 switches offer a number of benefits to hubs, such as the use of VLANs and each switch port is in
its own separate collision domain, thus eliminating collisions on the segment.
Which two commands will display the current IP address and basic Layer 1 and 2 status of an interface?
(Choose two.)
A. router#show version B. router#show ip interface C. router#show protocols D. router#show controllers E. router#show running-config
B. router#show ip interface
C. router#show protocols
Which two characteristics describe the access layer of the hierarchical network design model?
(Choose two.)
A. layer 3 support B. port security C. redundant components D. VLANs E. PoE
B. port security
D. VLANs
Explanation:
The primary function of an access-layer is to provide network access to the end user.
The hardware and software attributes of the access layer that support high availability include security
services for additional security against unauthorized access to the network through the use of tools such
as 802.1x, port security, DHCP snooping, Dynamic ARP Inspection, and IP Source Guard.
What is the purpose of assigning an IP address to a switch?
A. provides local hosts with a default gateway address
B. allows remote management of the switch
C. allows the switch to respond to ARP requests between two hosts
D. ensures that hosts on the same LAN can communicate with each other
B. allows remote management of the switch
Explanation:
Switch is a layer 2 device and doesn’t use network layer for packet forwarding. The IP address may be
used only for administrative purposes such as Telnet access or for network management purposes.
Which three statements are true about the operation of a full-duplex Ethernet network? (Choose three.)
A. There are no collisions in full-duplex mode.
B. A dedicated switch port is required for each full-duplex node.
C. Ethernet hub ports are preconfigured for full-duplex mode.
D. In a full-duplex environment, the host network card must check for the availability of the network media
before transmitting.
E. The host network card and the switch port must be capable of operating in full-duplex mode.
A. There are no collisions in full-duplex mode.
B. A dedicated switch port is required for each full-duplex node.
E. The host network card and the switch port must be capable of operating in full-duplex mode.
Explanation:
Half-duplex Ethernet is defined in the original 802.3 Ethernet and Cisco says you only use one wire pair
with a digital signal running in both directions on the wire. It also uses the CSMA/CD protocol to help
prevent collisions and to permit retransmitting if a collision does occur. If a hub is attached to a switch, it
must operate in half-duplex mode because the end stations must be able to detect collisions. Half-duplex
Ethernet–typically 10BaseT–is only about 30 to 40 percent efficient as Cisco sees it, because a large
10BaseT network will usually only give you 3- to 4Mbps–at most. Full-duplex Ethernet uses two pairs of
wires, instead of one wire pair like half duplex. Also, full duplex uses a point-to-point connection between
the transmitter of the transmitting device and the receiver of the receiving device, which means that with
full-duplex data transfer, you get a faster data transfer compared to half duplex. And because the
transmitted data is sent on a different set of wires than the received data, no collisions occur. The reason
you don’t need to worry about collisions is because now Full-duplex Ethernet is like a freeway with
multiple lanes instead of the single-lane road provided by half duplex. Full-duplex Ethernet is supposed to
offer 100 percent efficiency in both directions; this means you can get 20Mbps with a 10Mbps Ethernet
running full duplex, or 200Mbps for FastEthernet.
Which router command can be used to determine the status of Serial 0/0?
A. show ip route B. show interfaces C. show s0/0 status D. debug s0/0 E. show run F. show version
B. show interfaces
What is the subnet address of 172.16.159.159/22?
A. 172.16.0.0 B. 172.16.128.0 C. 172.16.156.0 D. 172.16.159.0 E. 172.16.159.128 F. 172.16.192.0
C. 172.16.156.0
Explanation:
Converting to binary format it comes to
11111111.11111111.11111100.00000000 or 255.255.252.0
Starting with 172.16.0.0 and having increment of 4 we get.
An administrator is working with the 192.168.4.0 network, which has been subnetted with a /26 mask.
Which two addresses can be assigned to hosts within the same subnet? (Choose two.)
A. 192.168.4.61 B. 192.168.4.63 C. 192.168.4.67 D. 192.168.4.125 E. 192.168.4.128 F. 192.168.4.132
C. 192.168.4.67
D. 192.168.4.125
Explanation:
Only the values of host with 67 and 125 fall within the range of /26 CIDR subnet mask, all others lie
beyond it.
What is the network address for the host with IP address 192.168.23.61/28?
A. 192.168.23.0 B. 192.168.23.32 C. 192.168.23.48 D. 192.168.23.56 E. 192.168.23.60
C. 192.168.23.48
Explanation:
convert bit-length prefix to quad-dotted decimal representation, then from it find the number of bits used for subnetting you can find previously calculated number of subnets by separating subnets each having
value of last bit used for subnet masking Find that your IP address is in which subnet, that subnet’s first
address is network address and last address is broadcast address. Based on above steps the answer is option C.
What is the best practice when assigning IP addresses in a small office of six hosts?
A. Use a DHCP server that is located at the headquarters.
B. Use a DHCP server that is located at the branch office.
C. Assign the addresses by using the local CDP protocol.
D. Assign the addresses statically on each node.
D. Assign the addresses statically on each node.
Explanation:
Its best to use static addressing scheme where the number of systems is manageable rather than use
dynamic protocol as it is easy to operate and manage.
Which two statements describe the IP address 10.16.3.65/23? (Choose two.)
A. The subnet address is 10.16.3.0 255.255.254.0.
B. The lowest host address in the subnet is 10.16.2.1 255.255.254.0.
C. The last valid host address in the subnet is 10.16.2.254 255.255.254.0
D. The broadcast address of the subnet is 10.16.3.255 255.255.254.0.
E. The network is not subnetted.
B. The lowest host address in the subnet is 10.16.2.1 255.255.254.0.
D. The broadcast address of the subnet is 10.16.3.255 255.255.254.0.
Explanation:
The mask 255.255.254.0 (/23) used with a Class A address means that there are 15 subnet bits and 9
host bits. The block size in the third octet is 2 (256 - 254). So this makes the subnets in 0,2, 4, 6, etc., all
the way to 254. The host 10.16.3.65 is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through3.254
Given a Class C IP address subnetted with a /30 subnet mask, how many valid host IP addresses are
available on each of the subnets?
A. 1 B. 2 C. 4 D. 8 E. 252 F. 254
B. 2
Explanation:
/30 CIDR corresponds to mask 55.255.255.252 whose binary is 11111100 which means 6 subnet bits and
2 host bits which means 62 subnets and 2 hosts per subnet.
Which one of the following IP addresses is the last valid host in the subnet using mask
255.255.255.224?
A. 192.168.2.63 B. 192.168.2.62 C. 192.168.2.61 D. 192.168.2.60 E. 192.168.2.32
B. 192.168.2.62
Explanation:
With the 224 there are 8 networks with increments of 32 One of these is 32 33 62 63 where 63 is broadcast so 62 is last valid host out of given choices.
An administrator is in the process of changing the configuration of a router.
What command will allow the administrator to check the changes that have been made prior to saving the
new configuration?
A. Router# show startup-config B. Router# show current-config C. Router# show running-config D. Router# show memory E. Router# show flash F. Router# show processes
C. Router# show running-config
Explanation:
This command followed by the appropriate parameter will show the running config hence the admin will
be able to see what changes have been made, and then they can be saved.
Which statements accurately describe CDP? (Choose three.)
A. CDP is an IEEE standard protocol.
B. CDP is a Cisco proprietary protocol.
C. CDP is a datalink layer protocol.
D. CDP is a network layer protocol.
E. CDP can discover directly connected neighboring Cisco devices.
F. CDP can discover Cisco devices that are not directly connected.
B. CDP is a Cisco proprietary protocol.
C. CDP is a datalink layer protocol.
E. CDP can discover directly connected neighboring
Explanation:
CDP (Cisco Discovery Protocol) is a proprietary protocol designed by Cisco to help administrators collect information about both locally attached and remote devices. By using CDP, you can gather hardware and protocol information about neighbor devices containing useful info for troubleshooting and documenting the network.
On a live network, which commands will verify the operational status of router interfaces? (Choose
two.)
A. Router# show interfaces B. Router# show ip protocols C. Router# debug interface D. Router# show ip interface brief E. Router# show start
A. Router# show interfaces
D. Router# show ip interface brief
Explanation:
Both these commands will show the current status of the interfaces, either in show or debug mode both
will display the information.
Which router command will configure an interface with the IP address 10.10.80.1/19?
A. router(config-if)# ip address 10.10.80.1/19
B. router(config-if)# ip address 10.10.80.1 255.255.0.0
C. router(config-if)# ip address 10.10.80.1 255.255.255.0
D. router(config-if)# ip address 10.10.80.1 255.255.224.0
E. router(config-if)# ip address 10.10.80.1 255.255.240.0
F. router(config-if)# ip address 10.10.80.1 255.255.255.240
D. router(config-if)# ip address 10.10.80.1 255.255.224.0
Explanation:
255.255.224 equal /19 in CIDR format hence the answer
What two things does a router do when it forwards a packet? (Choose two.)
A. switches the packet to the appropriate outgoing interfaces B. computes the destination host address C. determines the next hop on the path D. updates the destination IP address E. forwards ARP requests
A. switches the packet to the appropriate outgoing interfaces
C. determines the next hop on the path
Explanation:
Without following these two processes namely switching the packet to appropriate interface and telling the packet where to go by providing it with a destination IP address, the purpose of the same would not be solved.
Which two of these functions do routers perform on packets? (Choose two.)
A. examine the Layer 2 headers of inbound packets and use that information to determine the next hops
for the packets
B. update the Layer 2 headers of outbound packets with the MAC addresses of the next hops
C. examine the Layer 3 headers of inbound packets and use that information to determine the next hops
for the packets
D. examine the Layer 3 headers of inbound packets and use that information to determine the complete
paths along which the packets will be routed to their ultimate destinations
E. update the Layer 3 headers of outbound packets so that the packets are properly directed to valid next
hops
F. update the Layer 3 headers of outbound packets so that the packets are properly directed to their
ultimate destinations
B. update the Layer 2 headers of outbound packets with the MAC addresses of the next hops
C. examine the Layer 3 headers of inbound packets and use that information to determine the next hops
for the packets
Explanation:
This is the basic function of the router to receive incoming packets and then forward them to their required destination. This is done by reading layer 3 headers of inbound packets and update the info to layer 2 for further hopping.
Which statements are true regarding ICMP packets? (Choose two.)
A. They acknowledge receipt of TCP segments.
B. They guarantee datagram delivery.
C. TRACERT uses ICMP packets.
D. They are encapsulated within IP datagrams.
E. They are encapsulated within UDP datagrams.
C. TRACERT uses ICMP packets.
D. They are encapsulated within IP datagrams.
Explanation:
Ping may be used to find out whether the local machines are connected to the network or whether a
remote site is reachable. This tool is a common network tool for determining the network connectivity
which uses ICMP protocol instead of TCP/IP and UDP/IP. This protocol is usually associated with the
network management tools which provide network information to network administrators, such as ping
and traceroute (the later also uses the UDP/IP protocol). ICMP is quite different from the TCP/IP and
UDP/IP protocols. No source and destination ports are included in its packets. Therefore, usual packet-filtering rules for TCP/IP and UDP/IP are not applicable. Fortunately, a special “signature” known as the packet’s Message type is included for denoting the purposes of the ICMP packet. Most commonly used message types are namely, 0, 3, 4, 5, 8, 11, and 12 which represent echo reply, destination unreachable, source quench, redirect, echo request, time exceeded, and parameter problem respectively. In the ping service, after receiving the ICMP “echo request” packet from the source location, the destination
The command ip route 192.168.100.160 255.255.255.224 192.168.10.2 was issued on a router. No routing protocols or other static routes are configured on the router. Which statement is true about this command?
A. The interface with IP address 192.168.10.2 is on this router.
B. The command sets a gateway of last resort for the router.
C. Packets that are destined for host 192.168.100.160 will be sent to 192.168.10.2.
D. The command creates a static route for all IP traffic with the source address 192.168.100.160.
C. Packets that are destined for host 192.168.100.160 will be sent to 192.168.10.2.
Explanation:
160 it’s actually network address of /27 so any address within the range of 160 network will be sent to
192.168.10.2
What does administrative distance refer to?
A. the cost of a link between two neighboring routers
B. the advertised cost to reach a network
C. the cost to reach a network that is administratively set
D. a measure of the trustworthiness of a routing information source
D. a measure of the trustworthiness of a routing information source
Explanation:
Administrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of
the trustworthiness of the source of the routing information. The smaller the administrative distance value, the more reliable the protocol.
Which IOS command is used to initiate a login into a VTY port on a remote router?
A. router# login B. router# telnet C. router# trace D. router# ping E. router(config)# line vty 0 5 F. router(config-line)# login
B. router# telnet
Explanation:
VTY ports are telnet ports hence command B will initiate login to the telnet port.
In the configuration of NAT, what does the keyword overload signify?
A. When bandwidth is insufficient, some hosts will not be allowed to access network translation.
B. The pool of IP addresses has been exhausted.
C. Multiple internal hosts will use one IP address to access external network resources.
D. If the number of available IP addresses is exceeded, excess traffic will use the specified address pool.
C. Multiple internal hosts will use one IP address to access external network resources.
Explanation:
Overload simply means using multiple hosts to access the network using the same translated IP address.
What happens when computers on a private network attempt to connect to the Internet through a
Cisco router running PAT?
A. The router uses the same IP address but a different TCP source port number for each connection.
B. An IP address is assigned based on the priority of the computer requesting the connection.
C. The router selects an address from a pool of one-to-one address mappings held in the lookup table.
D. The router assigns a unique IP address from a pool of legally registered addresses for the duration of
the connection.
A. The router uses the same IP address but a different TCP source port number for each connection.
Explanation:
Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific
port on a local address. That is, both the address and the port numbers are translated. Static PAT is the
same as static NAT, except that it enables you to specify the protocol (TCP or UDP) and port for the real
and mapped addresses. Static PAT enables you to identify the same mapped address across many
different static statements, provided that the port is different for each statement. You cannot use the same
mapped address for multiple static NAT statements. Port Address Translation makes the PC connect to
the Internet but using different TCP source port.
When configuring NAT, the Internet interface is considered to be what?
A. local
B. inside
C. global
D. outside
D. outside
Explanation:
Network address translation or NAT requires the Internet to be considered as an outside interface else it
won’t serve the purpose it intends to.
The ip helper-address command does what?
A. assigns an IP address to a host
B. resolves an IP address from a DNS server
C. relays a DHCP request across networks
D. resolves an IP address overlapping issue
C. relays a DHCP request across networks
Explanation:
When the DHCP client sends the DHCP request packet, it doesn’t have an IP address. So it uses the
all-zeroes address, 0.0.0.0, as the IP source address. And it doesn’t know how to reach the DHCP server,
so it uses a general broadcast address, 255.255.255.255, for the destination. So the router must replace the source address with its own IP address, for the interface that received the request. And it replaces the destination address with the address specified in the ip helper- address command. The client device’s MAC address is included in the payload of the original DHCP request packet, so the router doesn’t need to do anything to ensure that the server receives this information.
The following commands are entered on the router:
Burbank(config)# enable secret fortress
Burbank(config)# line con 0
Burbank(config-line)# login
Burbank(config-line)# password n0way1n
Burbank(config-line)# exit
Burbank(config)# service password-encryption
What is the purpose of the last command entered?
A. to require the user to enter an encrypted password during the login process
B. to prevent the vty, console, and enable passwords from being displayed in plain text in the configuration files
C. to encrypt the enable secret password
D. to provide login encryption services between hosts attached to the router
B. to prevent the vty, console, and enable passwords from being displayed in plain text in the configuration files
Explanation:
Certain types of passwords, such as Line passwords, by default appear in clear text in the configuration
file. You can use the service password-encryption command to make them more secure. Once this
command is entered, each password configured is automatically encrypted and thus rendered illegible
inside the configuration file (much as the Enable/Enable Secret passwords are). Securing Line passwords
is doubly important in networks on which TFTP servers are used, because TFTP backup entails routinely
moving config files across networks–and config files, of course, contain Line passwords.
What is the effect of using the service password-encryption command?
A. Only the enable password will be encrypted.
B. Only the enable secret password will be encrypted.
C. Only passwords configured after the command has been entered will be encrypted.
D. It will encrypt the secret password and remove the enable secret password from the configuration.
E. It will encrypt all current and future passwords.
E. It will encrypt all current and future passwords.
Explanation:
Encryption further adds a level of security to the system as anyone having access to the database of
passwords cannot reverse the process of encryption to know the actual passwords which isn’t the case if
the passwords are stored simply.
An administrator has connected devices to a switch and, for security reasons, wants the dynamically
learned MAC addresses from the address table added to the running configuration. What must be done to accomplish this?
A. Enable port security and use the keyword sticky.
B. Set the switchport mode to trunk and save the running configuration.
C. Use the switchport protected command to have the MAC addresses added to the configuration.
D. Use the no switchport port-security command to allow MAC addresses to be added to the configuration.
A. Enable port security and use the keyword sticky.
Explanation:
One can configure MAC addresses to be sticky. These can be dynamically learned or manually
configured, stored in the address table, and added to the running configuration. If these addresses are
saved in the configuration file, the interface does not need to dynamically relearn them when the switch
restarts, hence enabling security as desired.
A company has placed a networked PC in a lobby so guests can have access to the corporate
directory. A security concern is that someone will disconnect the directory PC and re-connect their laptop
computer and have access to the corporate network.
For the port servicing the lobby, which three configuration steps should be performed on the switch to
prevent this? (Choose three.)
A. Enable port security.
B. Create the port as a trunk port.
C. Create the port as an access port.
D. Create the port as a protected port.
E. Set the port security aging time to 0.
F. Statically assign the MAC address to the address table.
G. Configure the switch to discover new MAC addresses after a set time of inactivity.
A. Enable port security.
C. Create the port as an access port.
F. Statically assign the MAC address to the address table.
Explanation:
If port security is enabled and the port is only designated as access port, and finally static MAC address is
assigned, it ensures that even if a physical connection is done by taking out the directory PC and inserting
personal laptop or device, the connection cannot be made to the corporate network, hence ensuring
safety.
Why would a network administrator configure port security on a switch?
A. to prevent unauthorized Telnet access to a switch port
B. to prevent unauthorized hosts from accessing the LAN
C. to limit the number of Layer 2 broadcasts on a particular switch port
D. block unauthorized access to the switch management interfaces
B. to prevent unauthorized hosts from accessing the LAN
Explanation:
You can use the port security feature to restrict input to an interface by limiting and identifying MAC
addresses of the stations allowed to access the port. When you assign secure MAC addresses to a
secure port, the port does not forward packets with source addresses outside the group of defined
addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC
address, the workstation attached to that port is assured the full bandwidth of the port. If a port is
configured as a secure port and the maximum number of secure MAC addresses is reached, when the
MAC address of a station attempting to access the port is different from any of the identified secure MAC
addresses, a security violation occurs. Also, if a station with a secure MAC address configured or learned
on one secure port attempts to access another secure port, a violation is flagged.
How can you ensure that only the MAC address of a server is allowed by switch port Fa0/1?
A. Configure port Fa0/1 to accept connections only from the static IP address of the server.
B. Configure the server MAC address as a static entry of port security.
C. Use a proprietary connector type on Fa0/1 that is incomputable with other host connectors.
D. Bind the IP address of the server to its MAC address on the switch to prevent other hosts from spoofing
the server IP address.
B. Configure the server MAC address as a static entry of port security.
Explanation:
When the MAC address is configured as static entry, no other address is allowed.
Which IP addresses are valid for hosts belonging to the 10.1.160.0/20 subnet? (Choose three.)
A. 10.1.168.0 B. 10.1.176.1 C. 10.1.174.255 D. 10.1.160.255 E. 10.1.160.0 F. 10.1.175.255
A. 10.1.168.0
C. 10.1.174.255
D. 10.1.160.255
Explanation:
All IP address in IP ranges between: 10.1.160.1 and 10.1.175.254 are valid as shown below
Address: 10.1.160.0 00001010.00000001.1010 0000.00000000
Netmask: 255.255.240.0 =2011111111.11111111.1111 0000.00000000
Wildcard: 0.0.15.25500000000.00000000.0000 1111.11111111
Which implies that
Network: 10.1.160.0/20 00001010.00000001.1010 0000.00000000
HostMin: 10.1.160.100001010.00000001.1010 0000.00000001
HostMax: 10.1.175.25400001010.00000001.1010 1111.11111110
Broadcast: 10.1.175.25500001010.00000001.1010 1111.11111111
If a host experiences intermittent issues that relate to congestion within a network while remaining
connected, what could cause congestion on this LAN?
A. half-duplex operation
B. broadcast storms
C. network segmentation
D. multicasting
B. broadcast storms
Explanation:
A broadcast storm can consume sufficient network resources so as to render the network unable to
transport normal traffic.
Given an IP address of 192.168.1.42 255.255.255.248, what is the subnet address?
A. 192.168.1.8/29 B. 192.168.1.32/27 C. 192.168.1.40/29 D. 192.168.1.16/28 E. 192.168.1.48/29
C. 192.168.1.40/29
Explanation:
248 mask uses 5 bits (1111 1000)
42 IP in binary is (0010 1010)
The base subnet therefore is the lowest binary value that can be written without changing the output of an
AND operation of the subnet mask and IP…
1111 1000 AND
0010 1010 equals
0010 1000 - which is .40
/24 is standard class C mask.
adding the 5 bits from the .248 mask gives /29
Which OSI layer header contains the address of a destination host that is on another network?
A. application B. session C. transport D. network E. data link F. physical
Answer: D
Explanation:
Only network address contains this information. To transmit the packets the sender uses network address
and datalink address. But the layer 2 address represents just the address of the next hop device on the way to the sender. It is changed on each hop. Network address remains the same.
Which layer of the TCP/IP stack combines the OSI model physical and data link layers?
A. Internet layer
B. transport layer
C. application layer
D. network access layer
D. network access layer
Explanation:
The Internet Protocol Suite, TCP/IP, is a suite of protocols used for communication over the internet. The TCP/IP model was created after the OSI 7 layer model for two major reasons. First,the foundation of the
Internet was built using the TCP/IP suite and through the spread of theWorld Wide Web and Internet, TCP/IP has been preferred. Second, a project researched by the Department of Defense (DOD) consisted of creating the TCP/IP protocols. The DOD’s goal was to bring international standards which could not be met by the OSI model. Since the DOD was the largest software consumer and they preferred the TCP/IP suite, most vendors used this model rather then the OSI. Below is a side by side comparison of the TCP/IP and OSI models.
Which protocol uses a connection-oriented service to deliver files between end systems?
A. TFTP B. DNS C. FTP D. SNMP E. RIP
C. FTP
Explanation:
FTP is an acronym for File Transfer Protocol. As the name suggests, FTP is used to transfer files between
computers on a network. You can use FTP to exchange files between computer accounts, transfer files between an account and a desktop computer, or access online software archives
Which transport layer protocol provides best-effort delivery service with no acknowledgment receipt
required?
A. HTTP B. IP C. TCP D. Telnet E. UDP
E. UDP
Explanation:
UDP provides a connectionless datagram service that offers best-effort delivery, which means that UDP
does not guarantee delivery or verify sequencing for any datagrams. A source host that needs reliable
communication must use either TCP or a program that provides its own sequencing and acknowledgment
services.
Which layer of the OSI model controls the reliability of communications between network devices
using flow control, sequencing and acknowledgments?
A. Physical
B. Data-link
C. Transport
D. Network
C. Transport
What is the default administrative distance of the OSPF routing protocol?
A. 90 B. 100 C. 110 D. 120 E. 130 F. 170
C. 110
What is the subnet address for the IP address 172.19.20.23/28?
A. 172.19.20.0 B. 172.19.20.15 C. 172.19.20.16 D. 172.19.20.20 E. 172.19.20.32
C. 172.19.20.16
Wich command can you use to manually assign a static IPV6 address to a router interface?
A. ipv6 address PREFIX_1::1/64
B. ipv6 autoconfig 2001:db8:2222:7272::72/64
C. ipv6 autoconfig
D. ipv6 address 2001:db8:2222:7272::72/64
D. ipv6 address 2001:db8:2222:7272::72/64
The network administrator is using a Windows PC application that is called putty.exe for remote
communication to a switch for network troubleshooting.
Which two protocols could be used during this communication? (Choose two).
A. SNMP B. HTTP C. Telnet D. RMON E. SSH
C. Telnet
E. SSH
What should be part of a comprehensive network security plan?
A. Allow users to develop their own approach to network security.
B. Physically secure network equipment from potential access by unauthorized individuals.
C. Encourage users to use personal information in their passwords to minimize the likelihood of
passwords being forgotten.
D. Delay deployment of software patches and updates until their effect on end-user equipment is well
known and widely reported.
E. Minimize network overhead by deactivating automatic antivirus client updates.
B. Physically secure network equipment from potential access by unauthorized individuals.
Which two of these statements are true of IPv6 address representation? (Choose two.)
A. There are four types of IPv6 addresses: unicast, multicast, anycast, and broadcast.
B. A single interface may be assigned multiple IPv6 addresses of any type.
C. Every IPv6 interface contains at least one loopback address.
D. The first 64 bits represent the dynamically created interface ID.
E. Leading zeros in an IPv6 16 bit hexadecimal field are mandatory.
B. A single interface may be assigned multiple IPv6 addresses of any type.
C. Every IPv6 interface contains at least one loopback address.
Explanation:
A single interface may be assigned multiple addresses of any type (unicast, anycast, multicast). Every
IPv6-enabled interface must contain at least one loopback and one link-local address. Optionally, every
interface can have multiple unique local and global addresses.
IPv6 host addresses can be assigned in multiple ways:
Static configuration
Stateless autoconfiguration
DHCPv6
When IPv6 is used over Ethernet networks, the Ethernet MAC address can be used to generate the 64-bit interface ID for the host. This is called the EUI-64 address. Since MAC addresses use 48 bits, additional
bits must be inserted to fill the 64 bits required.
A network administrator cannot connect to a remote router by using SSH. Part of the show interfaces
command is shown.
router#show interfaces
Serial0/1/0 is up, line protocol is down
At which OSI layer should the administrator begin troubleshooting?
A. physical
B. data link
C. network
D. transport
B. data link
Explanation:
I think the indication here is “Serial 0 is up, line protocol is down”.
What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged
is not a correct answer. If you check the output of your “show interface serial 0” command again, you
should notice it as “Serial 0 is down, line protocol is down. Under the “show ip int brief” you should see status = down and protocol = down as opposed to up, down. Because you disconnected the cable, layer 1
will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a
cable unplugged is not a correct answer to “Serial 0 is up, line protocol is down”.
Which option is a valid IPv6 address?
A. 2001:0000:130F::099a::12a
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1
D. 2004:1:25A4:886F::1
Explanation:
IPv6 Address Notation
IPv6 addresses are denoted by eight groups of hexadecimal quartets separated by colons in between
them.
Following is an example of a valid IPv6 address:
2001:cdba:0000:0000:0000:0000:3257:9652
Any four-digit group of zeroes within an IPv6 address may be reduced to a single zero or altogether
omitted.
Therefore, the following IPv6 addresses are similar and equally valid:
2001:cdba:0000:0000:0000:0000:3257:9652
2001:cdba:0:0:0:0:3257:9652
2001:cdba::3257:9652
The URL for the above address will be of the form:
http://[2001:cdba:0000:0000:0000:0000:3257:9652]/
What is the purpose of the switchport command?
Switch(config-if)# switchport port-security maximum 1
Switch(config-if)# switchport port-security mac-address 0018.DE8B.4BF8
A. It ensures that only the device with the MAC address 0018.DE8B.4BF8 will be able to connect to the
port that is being configured.
B. It informs the switch that traffic destined for MAC address 0018.DE8B.4BF8 should only be sent to the
port that is being configured.
C. It will act like an access list and the port will filter packets that have a source or destination MAC of
0018.DE8B.4BF8.
D. The switch will shut down the port of any traffic with source MAC address of 0018.DE8B.4BF8.
A. It ensures that only the device with the MAC address 0018.DE8B.4BF8 will be able to connect to the
port that is being configured.
How many bits are contained in each field of an IPv6 address?
A. 24
B. 4
C. 8
D. 16
D. 16
One of the key advantages IPv6 brings is the exponentially larger address space. The following will
outline the basic address architecture of IPv6.
128-bit-long addresses
Represented in hexadecimal format:
Uses CIDR principles: prefix/prefix length x:x:x:x:x:x:x:x, where x is a 16-bit hex field The last 64 bits are
used for the interface ID
Which three approaches can be used while migrating from an IPv4 addressing scheme to an IPv6
scheme? (Choose three)
A. static mapping of IPv4 address to IPv6 addresses
B. configuring IPv4 tunnels between IPv6 islands
C. use DHCPv6 to map IPv4 addresses to IPv6 addresses
D. use proxying and translation (NAT-PT) to translate IPv6 packets into IPv4 packets
E. configure IPv6 directly
F. enable dual-stack routing
B. configuring IPv4 tunnels between IPv6 islands
D. use proxying and translation (NAT-PT) to translate IPv6 packets into IPv4 packets
F. enable dual-stack routing
Explanation:
Connecting IPv6 islands with tunnels
An IPv6 island is a network made of IPv6 links directly connected by IPv6 routers. In the early days of
IPv6 deployment, there are many IPv6 islands. IPv6 in IPv4 tunnels are used to connect those islands
together. In each island, one (or more) dual stack routers are designated to encapsulate and decapsulate IPv6 packets within IPv4 packets. Different mechanisms have been developed to manage tunnels: automatic tunnels3, configured tunnels3, tunnel brokers3, 6over43, 6to43,…
Network Address Translation - Protocol Translation (NAT-PT) The NAT-PT method enables the ability to
either statically or dynamically configure a translation of a IPv4 network address into an IPv6 network
address and vice versa. For those familiar with more typically NAT implementations, the operation is very
similar but includes a protocol translation function. NAT-PT also ties in an Application Layer Gateway
(ALG) functionality that converts Domain Name System (DNS) mappings between protocols.
Dual Stack
The simplest approach when transitioning to IPv6 is to run IPv6 on all of the devices that are currently
running IPv4. If this is something that is possible within the organizational network, it is very easy to
implement. However, for many organizations, IPv6 is not supported on all of the IPv4 devices; in these situations other methods must be considered.
Which statement about IPv6 is true?
A. Addresses are not hierarchical and are assigned at random.
B. Only one IPv6 address can exist on a given interface.
C. There are 2.7 billion addresses available.
D. Broadcasts have been eliminated and replaced with multicasts.
D. Broadcasts have been eliminated and replaced with multicasts.
Explanation:
IPv6 has three types of addresses, which can be categorized by type and scope: Unicast addresses. A
packet is delivered to one interface.
Multicast addresses. A packet is delivered to multiple interfaces.
Anycast addresses. A packet is delivered to the nearest of multiple interfaces (in terms of routing
distance).
IPv6 does not use broadcast messages.
Unicast and anycast addresses in IPv6 have the following scopes (for multicast addresses, the scope are
built into the address structure):
Link-local. The scope is the local link (nodes on the same subnet). Site-local. The scope is the
organization (private site addressing). Global. The scope is global (IPv6 Internet addresses). In addition,
IPv6 has special addresses such as the loopback address. The scope of a special address depends on
the type of special address. Much of the IPv6 address space is unassigned.
What are two recommended ways of protecting network device configuration files from outside
network security threats? (Choose two.)
A. Allow unrestricted access to the console or VTY ports.
B. Use a firewall to restrict access from the outside to the network devices.
C. Always use Telnet to access the device command line because its data is automatically encrypted.
D. Use SSH or another encrypted and authenticated transport to access device configurations.
E. Prevent the loss of passwords by disabling password encryption.
B. Use a firewall to restrict access from the outside to the network devices.
D. Use SSH or another encrypted and authenticated transport to access device configurations.
A receiving host has failed to receive all of the segments that it should acknowledge.
What can the host do to improve the reliability of this communication session?
A. decrease the window size
B. use a different source port for the session
C. decrease the sequence number
D. obtain a new IP address from the DHCP server
E. start a new session using UDP
A. decrease the window size
Which command enables IPv6 forwarding on a cisco router?
A. ipv6 host
B. ipv6 unicast-routing
C. ipv6 local
D. ipv6 neighbor
B. ipv6 unicast-routing
Explanation:
Enabling IPv6 on Cisco IOS Software Technology
The first step of enabling IPv6 on a Cisco router is the activation of IPv6 traffic forwarding to forward
unicast IPv6 packets between network interfaces. By default, IPv6 traffic forwarding is disabled on Cisco
routers.
The ipv6 unicast-routing command is used to enable the forwarding of IPv6 packets between interfaces
on the router.
The syntax for this command is as follows:
Router(config)#ipv6 unicast-routing
The ipv6 unicast-routing command is enabled on a global basis.
Identify the four valid IPv6 addresses. (Choose four.)
A. :: B. ::192:168:0:1 C. 2000:: D. 2001:3452:4952:2837:: E. 2002:c0a8:101::42 F. 2003:dead:beef:4dad:23:46:bb:101
A. ::
B. ::192:168:0:1
E. 2002:c0a8:101::42
F. 2003:dead:beef:4dad:23:46:bb:101
Which two statements describe characteristics of IPv6 unicast addressing? (Choose two.)
A. Global addresses start with 2000::/3.
B. Link-local addresses start with FE00:/12.
C. Link-local addresses start with FF00::/10.
D. There is only one loopback address and it is ::1.
E. If a global address is assigned to an interface, then that is the only allowable address for the interface.
A. Global addresses start with 2000::/3.
D. There is only one loopback address and it is ::1.
A network administrator is trying to add a new router into an established OSPF network. The
networks attached to the new router do not appear in the routing tables of the other OSPF routers.
Given the information in the partial configuration shown below, what configuration error is causing this
problem?
Router(config)# router ospf 1
Router(config-router)# network 10.0.0.0 255.0.0.0 area 0
A. The process id is configured improperly.
B. The OSPF area is configured improperly.
C. The network wildcard mask is configured improperly.
D. The network number is configured improperly.
E. The AS is configured improperly.
F. The network subnet mask is configured improperly.
C. The network wildcard mask is configured improperly.
Explanation:
When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access
list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”
Which statement is true?
A. An IPv6 address is 64 b long and is represented as hexadecimal characters.
B. An IPv6 address is 32 b long and is represented as decimal digits.
C. An IPv6 address is 128 b long and is represented as decimal digits.
D. An IPv6 address is 128 b long and is represented as hexadecimal characters.
D. An IPv6 address is 128 b long and is represented as hexadecimal characters.
Which of the following describe the process identifier that is used to run OSPF on a router? (Choose
two)
A. It is locally significant.
B. It is globally significant.
C. It is needed to identify a unique instance of an OSPF database.
D. It is an optional parameter required only if multiple OSPF processes are running on the router.
E. All routers in the same OSPF area must have the same process ID if they are to exchange routing
information.
A. It is locally significant.
C. It is needed to identify a unique instance of an OSPF database.
Explanation:
They are locally significant only, and have no bearing on the structure of any OSPF packet or LSA update.
So you can have a separate process-id on every single router in your network if you so desire!
Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks
by the Interior Gateway Protocol (IGP) working group of the Internet Engineering Task Force (IETF).
What is the default administrative distance of the OSPF routing protocol?
A. 90 B. 100 C. 110 D. 20 E. 130 F. 170
C. 110
Which address are OSPF hello packets addressed to on point-to-point networks?
A. 224.0.0.5 B. 172.16.0.1 C. 192.168.0.5 D. 223.0.0.1 E. 254.255.255.255
A. 224.0.0.5
Explanation:
Why Does the show ip ospf neighbor Command Reveal Neighbors in the Init State?
OSPF hello packets have a destination address of 224.0.0.5 (the all ospf routers multicast address).
Which statements describe the routing protocol OSPF? (Choose three)
A. It supports VLSM.
B. It is used to route between autonomous systems.
C. It confines network instability to one area of the network.
D. It increases routing overhead on the network.
E. It allows extensive control of routing updates.
F. It is simpler to configure than RIP v2.
A. It supports VLSM.
C. It confines network instability to one area of the network.
E. It allows extensive control of routing updates.
Explanation:
The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector
based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new
concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth. OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is
flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an
area.
Why do large OSPF networks use a hierarchical design? (Choose three.)
A. to decrease latency by increasing bandwidth
B. to reduce routing overhead
C. to speed up convergence
D. to confine network instability to single areas of the network
E. to reduce the complexity of router configuration
F. to lower costs by replacing routers with distribution layer switches
B. to reduce routing overhead
C. to speed up convergence
D. to confine network instability to single areas of the network
Explanation:
OSPF implements a two-tier hierarchical routing model that uses a core or backbone tier known as area
zero (0). Attached to that backbone via area border routers (ABRs) are a number of secondary tier areas.
The hierarchical approach is used to achieve the following:
- Rapid convergence because of link and/or switch failures
- Deterministic traffic recovery
- Scalable and manageable routing hierarchy, reduced routing overhead.
A router has learned three possible routes that could be used to reach a destination network. One
route is from EIGRP and has a composite metric of 20514560. Another route is from OSPF with a metric
of 782. The last is from RIPv2 and has a metric of 4.
Which route or routes will the router install in the routing table?
A. the OSPF route B. the EIGRP route C. the RIPv2 route D. all three routes E. the OSPF and RIPv2 routes
B. the EIGRP route
Explanation:
When one route is advertised by more than one routing protocol, the router will choose to use the routing
protocol which has lowest Administrative Distance.
Route Source Administrative Distance
Directly Connected 0
Static 1
EIGRP 90
EIGRP Summary Route 5
OSPF 110
RIP 120
Which command is used to display the collection of OSPF link states?
A. show ip ospf link-state
B. show ip ospf lsa database
C. show ip ospf neighbors
D. show ip ospf database
D. show ip ospf database
Explanation:
The “show ip ospf database” command displays the link states.
What is the default administrative distance of OSPF?
A. 90
B. 100
C. 110
D. 120
C. 110
Explanation:
Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.
