CcEnT Flashcards
Assist in PASSING the ICND1 640-822 exam
Administration of network equipment via a GUI browser commonly uses which two protocols?
HTTP & SSL
When data is sent via TCP, which two PDUs are encapsulated into bits on the wire?
TCP Segment & IP Packet
What is the “well-known” port number range that is used in TCP and UDP as assigned by the IANA?
0-1023
What does the Show Flash command do?
Lists the files in flash memory along with the size, available space, and type of flash memory
What is the purpose of the Debug command?
It provides a flow of dynamic information about the status of a device that keeps updating.
Which Global command adds time stamps to log messages including debug messages?
service timestamps
Command used to disable an unused port?
shutdown
A VoIP call requires what kind of connection?
Low latency/delay, low jitter, no loss
What are the three VTP modes and which two allow VLANs to be added, modified, and deleted?
Server, client and transparent modes. Server & transparent allow changes to be made.
What two situations would likely cause a serial interface to have the status of’ “Serial 1 is up, line protocol is down”
No keepalives and a mismatched encapsulation type
Characteristics of TCP:
Lost or corrupted packets are retransmitted
A TCP segment contains a SEQuence # and an ACKnowledgement #
What is WEP?
Wired Equivalent Privacy is a security algorithm used in wireless networks that uses a 40 bit key. It also has a 128 bit key version. It is easily broken and not recommended for use.
In which layer of the OSI model would you begin troubleshooting problems with IP addressing?
Layer 3, the Network layer is where IP works
What is the command to associate the extended IPv4 ACL 100 to interface FastEthernet 0/0?
ip access-group 100 in Note: only one ACL per protocol, per direction and per interface is allowed.
Which ACL type is known to be the most efficient?
The inbound type because it would be closest to the origin and discard packets before consuming router resources.
What is NAT used for?
Network Address Translation is used to modify a private IP address in the IPv4 header to a public IP address while in transit across a network routing device. It protects private hosts.
Name the one or more OSI model layers that match the TCP/IP model layer 4
TCP/IP layer 4, the Application layer, maps to the OSI layers 5-7, the Session, Presentation, and Application layers.
Name the one or more OSI model layers that match the TCP/IP model layer 3
TCP/IP layer 3, the Transport layer, maps to OSI layer 4, the Transport layer.
Name the one or more OSI model layers that match the TCP/IP model layer 2
TCP/IP layer 2, the Internetworking or Internet layer, maps to OSI layer 3, the Network layer
Name the one or more OSI model layers that match the TCP/IP model layer 1
TCP/IP layer 1, the Link or Network access layer, maps to OSI layers 2 and 1, the Data Link and Physical layers.
What services does Windowing provide?
The sender can send a specified number (the window size - 1) of unacknowledged frames.
This is a good method to address physical security threats
Control server room access
Describe the basic differences between various 802.11 wireless standards
- 11a = 54Mbps max., 5GHz, OFDM
- 11b = 11Mbpsmax., 2.4GHz, DSSS
- 11g = 54Mbps max., 2.4GHz, OFDM&DSSS
- 11n = 150Mbps max, 2.4/5GHz, OFDM
This type of attack is considered an access attack
A password attack
Possible impact of poor cable management on a network?
RJ-45 connectors are stressed, causing wires to break
Purpose of the configuration register?
The configuration register is a special 16 bit number that can be set on any Cisco router. Some of the uses include specifying the location of the iOS s/w image and to help in pwd recovery
What do the commands Ctrl+Shift+6 and Ctrl+Shift+6x do regarding Telnet?
Ctrl+Shift+6 terminates looping commands such as an extended ping. Ctrl+Shift+6x initiates a reverse Telnet session back to the original router (e.g. R1 to R2 then back to R1)
You need to connect multiple physically remote LANs together with a WAN. What network device will allow remote LANs to communicate?
A router
When 2 PCs are separated by 1 or more routers, what are 2 things that must be true?
The PCs must be on different subnets and the PCs must have a default gateway setup on their local router.
What is the difference between the Login and Login Local commands?
The use of the Login command on an interface or line tells iOS to prompt for a password; the Login Local command tells iOS to prompt for a username and password to be checked against locally configured username global config commands.
When using the Show IP Interface Brief command, what does OK? YES or NO indicate?
OK? refers to whether the interface has a valid configuration, so YES means it does have a valid config, NO means it does not have a valid config
What are the various router interface status codes and their meanings?
Admin. Down & Down = has a shutdown command config. on it. Down & Down = no shut is config, but phys layer down (no cable, no power etc) Up & Down = data link layer prob (mismatched encapsulation or clockrate mismatches or no keepalives) Up & Up = OK
On a Cisco router, switch etc. What is the purpose of the ? command?
The question mark command reveals the command options when used with a command or shows available commands at that location
Specify two commands that allow you to create a new configuration using Setup Mode
1=Router#setup
and
2=Router#erase startup-config
Router#reload
What are the two DSL types that all others are a variation of?
Asynchronous or ADSL (Upload & Download NOT the same) and Synchronous or SDSL (Are the same). ADSL usually down faster, up slower.
If the DHCP server is setup but disabled on your Cisco router, how do you turn it back on?
Router(config)#service dhcp
What is the best choice of device to help a customer get 15 computers to commun. as fast as possible?
A switch
3 statements that describe WANs
- WANs connect devices that are separated by wide geographic areas. 2. WANs can use cable and satellite companies. 3. WANs use serial connections of various interface types.
In a SOHO network, what common device is required to connect the LAN to various different high-speed Internet access services?
A router
What is the purpose of configuring a default gateway in a Cisco Catalyst switch?
To specify the IP address of the router that will forward requests made to the mgmt IP address of the switch from devices on other subnets.
show cdp
states whether CDP is enabled globally and list the default update and holdtime timers
show cdp entry {name}
lists the same info as “show cdp neighbors detail” but for the {name} neighbor only
show cdp interface (option: type&# e.g. fa0/1)
states whether CDP is enabled on each interface, (or on a specific interface if specified) and states the status and update and holdtime timers on those interfaces along with encapsulation type
show cdp neighbors (option: type&# e.g. fa0/1)
lists one summary line of info about each neighbor (or just about the neighbor on the specified interface)
show cdp neighbors detail
lists one large set (approx 15 lines) of info about each neighbor incl: device ID, IP addr, platform, capabilities, interface, port ID, holdtime, IOS ver
show cdp traffic
lists global statistics for the # of CDP advertisements sent and received
cdp run & no cdp run
to globally enable cdp or globally disable cdp, used at the config-t (config) level
cdp enable and no cdp enable
to enable or disable cdp on an interface, used on the (config-if) level for the device
What is CDP?
Cisco Discovery Protocol is a proprietary protocol created by Cisco to discover information about directly connected Cisco devices (only), it works at layer 2 of the OSI model
What type of media is required to physically connect CDP devices?
Physical media that connect CDP devices must support Subnetwork Access Protocol (SNAP) encapsulation
How does a switch process data frames to be forwarded between ports?
A switch uses MAC address tables created from the source address of incoming ports (received from the port when it connected to the switch)
Describe characteristics about UDP
UDP: operates at layer 4, is connectionless; packets are processed independently, delivery not guaranteed, includes a pseudo-header that includes the dest.addr & an optional checksum value; lost or corrupted packets are not retransmitted
What amount of delay is considered tolerable for VoIP per ITU-T G.114 specs?
recommended tolerable one-way delay for voice is 150 ms, 200 ms in a private network, and don’t tolerate anything over 250 ms.
What utility can be used to rule out a duplicate IP address?
PING. Duplicate IP addresses are usually caused by manual IP address config. Remove the suspected device from the network (power down, disconnect) and ping the address. The dupl. device will answer. Then check the ARP table for the MAC address.
Unencrypted wireless traffic on an AP could allow a hacker to?
Eavesdrop on wireless traffic
Name the three types of ports on a router
Auxiliary/Console, Network and USB
All hosts have been active on a network for hours when the DHCP server goes down. What happens to the hosts that have obtained service from the DHCP server?
The hosts will continue to operate normally for a period of time (until their lease expires). Leases typically last for anywhere from hours to days.
What does the “copy tftp flash” command do?
It downloads a copy of the IOS from a tftp server to the flash memory of a Cisco device. If there is not enough memory avail. it erases the current IOS file from the device during the copy process, then downloads the new copy.
Characteristics of the OSPF protocol
Open Shortest Path First is an open standard, link-state routing protocol. OSPF uses a 2 layer network hierarchy that has 2 primary elements: Autonomous System (AS) aka domain, which is a collection of ntwrks with a common admin, and Area, which is a grouping of contiguous ntwrks. An AS can have multiple Areas or logical subdivisions
What does the “show controllers” command do?
Show Controllers is one of the few commands useful for troubleshooting serial interface connections. If, for example, you see an interface is shut down, you would No Shut that interface from the (config-if) command prompt.
5 elements of the Cisco Unified Wireless Network
Client devices, Access Points (APs), Network Unification, Network Mgmt., Mobility Services
4 Switch Series that still use CatOS
2900G, 4000, 5000 & 6000 series
8 IOS Switch series
1900 & 2800, 2900XL & 2950; 3500 & 3550, 4500 & 6500
4 Commands, in order, to enable Telnet
Config T; line vty 0 15; login; password
5 steps in the correct execution sequence for deploying wireless LANs
- Verify existing wired ntwk; 2. Install & config the AP to the wired ntwk; 3. Config the AP’s wireless settings; 4. Install & config wireless clients; 5. Verify & test wireless LAN
List of well known port numbers & TCP or UDP
20 FTP data: TCP | 21 FTP control: TCP 22 SSH: TCP | 23 Telnet: TCP 25 SMTP: TCP | 53 DNS: TCP & UDP 67, 68 DHCP:UDP | 69 TFTP: UDP 80 HTTP: TCP | 110 POP3 TCP 161 SNMP: UDP | 443 SSL: TCP 16,328 - 32,767 RTP based VoIP and Video
