Chapter 3 Flashcards
What is NOT one of the three characteristics of TCP in its role as a reliable delivery protocol? A) Connection-oriented Protocol B) Sequencing and checksums C) Framing D) Flow Control
C) Framing
What field in an IPv4 packet informs routers the level of precedence they should apply when processing an incoming packet? A) Differentiated Services (DiffServ) B) Internet header length (IHL) C) Time to Live (TTL) D) Padding
A) Differentiated Services (DiffServ)
A modern ASN consists of how many bits? A) 16 B) 32 C) 64 D) 128
B) 32
What netstat command option lists only current connections, including IP addresses and port numbers? A) -s B) -r C) -n D) -o
C) -n
By default, the pathping command sends how many pings per hop? A) 50 B) 100 C) 200 D) 500
B) 100
Which network routing protocol is a path vector protocol that sends updates between routers using TCP? A) IS-IS B) OSPF C) RIP D) BGP
D) BGP
At what layer of the OSI model would a TCP or UDP header be added to a payload? A) Layer 7 B) Layer 4 C) Layer 2 D) Layer 1
B) Layer 4
In a TCP segment, what field indicates how many bytes the sender can issue to a receiver while acknowledgement for the segment is outstanding? A) urgent pointer B) sliding window C) sequence number D) URG flag
B) sliding window
Which of the following is not a task handled by a router?
A) A router forwards broadcasts over the network
B) A router can reroute traffic if the path of first choice is down but a second path is available
C) A router can interpret Layer 3 and often Layer 4 addressing
D) A router can connect dissimilar networks
A) A router forwards broadcasts over the network
The IP connectionless protocol relies on what other protocol to guarantee delivery of data> A) UDP B) ICMP C) TCP D) ARP
C) TCP
What command can be used on a Cisco router to view the routing table? A) route print B) netstat -r C) route D) show ip route
D) show ip route
What parameter can be combined with the traceroute command to instruct it to use ICMP echo requests instead of UDP datagrams? A) -n B) -p C) -i D) -d
C) -i
What TCP field below allows the receiving node to determine whether a TCP segment is corrupted during transmission? A) checksum B) sliding window C) acknowledgement number D) TCP header length
A) checksum
What happens when a router receives a packet with a TTL of 0?
A) The router attempts to forward the traffic on a local network
B) The router drops the packet and sends an ICMP TTL expired message back to the host
C) The router resets the TTL to 128
D) The router marks the packet as corrupted and forwards it to the next hop
B) The router drops the packet and sends an ICMP TTL expired message back to the host
What IPv4 protocol handles multicasting for tasks such as videoconferencing or teleconferencing? A) ICMP B) ARP C) TCP D) IGMP
D) IGMP
When viewing the routing table on a UNIX system, what flag indicates if a route is a usable route? A) I B) H C) G D) U
D) U
What routing protocol criteria is defined as the time it takes to recognize a best path change in the event of a network outage? A) administrative distance detection B) convergence time C) overhead calculation D) downed path detection
B) convergence time
What type of routing protocol enables routers to communicate beyond neighboring routers, allowing each router to create a map of an entire network? A) distance vector B) link state C) exterior gateway D) map extension
B) link state
What address does ARP work in conjunction with IPv4 to discover? (2) A) IP B) MAC C) ARP D) physical
B) MAC
D) physical
Which of the following are types of entries an ARP table contains? (2) A) Static B) Flat C) Basic D) Dynamic
A) Static
D) Dynamic
What versions of the IP protocol are used on networks today? A) IPv1 B) IPv4 C) IPv6 D) IPv5
B) IPv4
C) IPv6
Which layers of the OSI model are all routers able to interpret? A) 1 B) 2 C) 3 D) 4
C) 3
D) 4
What is the sliding window size
Indicates how many bites the sender can issue to a receiver while acknowledgement for this segment is outstanding
16 bits
What is checksum
Allows the receiving node to determine whether the TCP segment became corrupted
what is an Urgent Pointer
Indicates a location in the data were urgent data resides.
What is TCP header
Contains filler information to ensure that the size of the TCP header is a multiple of 32 bits
How many fields are there in the TCP header
10 Fields
How many fields are there is the UDP header
4 Fields
What is the difference between a Datagram and a Packet
A datagram is a message that stands alone delivery is not guaranteed and no prior transmission was required
A packet is entire message which includes the segment and header
What is the flags flied in the IPv4 packet
Indicates whether a message is fragmented and if it is fragmented whether this packet is the last in the fragment
What is the fragment offset in the IPv4 packet
identifies where the packet fragment belongs in the incoming set of fragments
What is the Time to live (TTL) field in the IPv4 packet
Indicates the maximum duration that the packet can remain on the network before it is discarded
What is the protocol field in the IPv4 packet
Identifies the type of protocol that will receive the packet
What is the header checksum in the IPv4 field
Allows the receiving host to calculate whether the IP header has been corrupted during transmission
What is the padding field in the IPv4 packet
Contains filter bits to ensure that the header is a multiple of 32 bits
What is the Internet header length IHL in the IPv4 packet
Indicates the length of the TCP header in bytes. The header can be 20 to 60 bytes.
What is the differentiated services field in the the IPv4 packet
Informs routers the level of precedence they should apply when processing the incoming packet
What is the traffic class field in the IPv6 packet
Identifies the packet’s priority
What is the flow label field in the the IPv6 Packet
Indicates which flow or sequence of packets from one source to one or multiple destinations the packet belongs to.
What is the Payload length field in the IPv6 packet
Indicates the size of the payload or data carried by the packet
What is the Next Header field in the IPv6 fields
Identifies the type of header that immediately follows the IP packet header.
What is the Hop Limit field in the IPv6 packet
Indicates the number of times that the packet can be forwarded by the routers
What 2 protocols only work with IPv4
IGMP - Internet Group Management Protocol
ARP - Address Resolution Protocol
What Protocol is utilized by both IPv4 and IPv6
ICMP - Internet Control Message Protocol
What is the ICMP
In the Network Layer
Report the success or failure of message deliver
What is IGMP
Internet Group Management Protocol
Operates in the Network Layer
Manages multi-casting
Router use IGMP to determine which nodes belong to certain multicast group and transmit data to all nodes in that group.
What is ARP
Address Resolution Protocol
Works with IPv4
Discovers the MAC address of a host
Is a Layer 2 protocol
What is the command to view ARP
ARP -a
ARP -a command shows
MAC addresses
What are the 3 types of Routers
Interior Routers
Border Routers
Exterior Routers
What are the characteristics of an Interior Router
Directs data btw networks in the sam autonomous system Autonomous Systems (AS) is a group of networks often on the same domain
What are the characteristics of the Border Routers
Connect an AS with an outside network
What are the characteristics of the Exterior Router
Direct data btw AS these routers operate on the internet backbone
What is Static Routing
Is a technique in which a network administrator configures a routing table to direct messages along specific paths btw networks
What is Dynamic Routing
Routers automatically calculates the best path between two networks and accumulates this information in the routing table.
What is a Default Gateway
Messages are sent to a router or layer 3 switch when their destination is not on the host’s local network
What is a default route
Is a backup route when no other route can de determined.
What is the route utility command
Windows - Route Print
Linux - route
Cisco show IP Route
What are some of the metrics used to determine the routing metrics
Hop count Bandwidth Latency MTU Routing Cost Topology of the network
What is MTU
Maximum transmission Unit
the largest IP packet size in bytes allowable
What is Administrative Distance
Each routing protocol is assigned as default AD, which is a number indicating the protocol reliability with the lowest number representing the higher priority
What is Convergence Time
The time is takes to recognize a best path in the event of a change or network outage
What is overhead
The burden placed on the underlying network to support the protocol
What are Routing Protocols based on
Administrative Distance
Convergence Time
Overhead
What are some of the common routing protocols
RIP - Routing Information Protocol RIPv2 Routing Information Protocol v2 OSPF Open Shortest Path First IS-IS Intermediate System to Intermediate System BGP Border Gateway Protocol
What are IGP’s
Interior Gateway Protocols - routing protocols used by interior routers with AS
Grouped according to
Distance - Vector Protocols
Link - State Routing Protocols
What is Distance - Vector Routing Protocols
Calculates the best path to a destination on the basis of the distance to that destination.
RIP and RIPv2 are distance - vector routing protocols
What are Link - State routine protocols
Enables routers to communicate beyond neighboring routers, after which each router can independently map the network
OSPF and IS-IS are link state routing protocols
What is EGP
Exterior gateway protocols
Used by border and exterior routers
distributes data outside the AS system
Uses BGP
What is the only routing protocol that communicates across the internet
BGP Border Gateway Protocol
Describe RIP
Oldest router protocol
Broadcast every 30 seconds creates excessive noise
Convergence time is poor
Factors only the number of HOPS btw nodes 15 maximum
Does not consider congestion
Describe RIPv2
Generates less broadcast traffic
function more securely then RIP
Can not exceed 15 HOPS
Describe OSPF
Open Shortest path First No HOP limits May change from shortest path to most efficient path Used on Interior and Border Routers Used for IPv4 only
Describe IS-IS
Intermediate System to Intermediate System
Uses best path
Designated for interior routers
Used for IPv4 and IPv6
Describe BGP
Border Gateway Protocol Protocol for the Internet Path - Vector routing protocol that communicates via BGP specific messages that travel between routers over TCP sessions Can span multiple AS Most complex protocol
What is NSLOOKUP
Query the nameserver for the IP address of the given HOST optionally using a specified DNS server
What is NETSTAT
Displays a list of all active TCP/IP connections on the local machine
What is NETSTAT -n
List current connections including IP addresses and port numbers
What is NETSTAT -f
List current connections including IP addresses and port numbers and FQDN’s
What is NETSTAT - p TCP
List current connections including IP addresses and port numbers and FQDN for a specific protocol
What is a NETSTAT -e
Displays statistics about messages sent over a network interface including errors and discards
What is a NETSTAT - s
Displays statistics about each messages transmitted by a host, separated according to the protocol type. IP, TCP , UDP and ICMP.
What is NETSTAT -r
Displays routing table information
What is NETSTAT -o
Lists the processor identifier (PID) for each process using a connection and information about the connection.
What is NETSTAT -b
List the name of each process using a connection and information about the connection. Requires an elevated command prompt.
What is NETBIOS
A windows protocol used as an alternative to TCP/IP
What is NBSTAT
A TCP/IP troubleshooting utility that provides information about the netbios names and their IP addresses
What is tracert or traceroute
A windows utility that uses ICMP echo requests to trace the path from one node to another
- UDP provides error checking, but not sequencing.
(A) True
(B) False
False
UDP provides error checking, but not sequencing.
(A) True
(B) False
Answer : (B)
IP is an unreliable, connectionless protocol.
(A) True
(B) False
Answer : (A)
IPv4 and IPv6 use the same packet format.
(A) True
(B) False
False
As a network support technician, you only need to know how to support IPv6.
(A) True
(B) False
True
On IPv4 networks, IGMP operates at the Network layer of the OSI model to manage multicasting.
(A) True
(B) False
True
What is NOT one of the three characteristics of TCP in its role as a reliable delivery protocol? (A) Connection-oriented Protocol (B) Sequencing and checksums (C) Framing (D) Flow Control
Framing
What field in an IPv4 packet informs routers the level of precedence they should apply when processing an incoming packet? (A) Differentiated Services (DiffServ) (B) Internet header length (IHL) (C) Time to Live (TTL) D) Padding
Differentiated Services (DiffServ)
A modern ASN consists of how many bits? (A) 16 (B) 32 (C) 64 (D) 128
(B) 32
What netstat command option lists only current connections, including IP addresses and port numbers? (A) -s (B) -r (C) -n (D) -o
Answer : (C)
By default, the pathping command sends how many pings per hop? (A) 50 (B) 100 C) 200 D) 500 Answer : (B)
Answer : (B)
Which network routing protocol is a path vector protocol that sends updates between routers using TCP? (A) IS-IS (B) OSPF (C) RIP (D) BGP Answer : (D)
Which network routing protocol is a path vector protocol that sends updates between routers using TCP? (A) IS-IS (B) OSPF (C) RIP (D) BGP Answer : (D)
What protocol replaces ARP, IGMP, and ICMPv4 on IPv6 based networks? (A) ARPng (B) BGPv6 (C) IGMPv6 (D) ICMPv6
Answer : (D)
At what layer of the OSI model would a TCP or UDP header be added to a payload? (A) Layer 7 (B) Layer 4 (C) Layer 2 (D) Layer 1
Answer : (B)
In a TCP segment, what field indicates how many bytes the sender can issue to a receiver while acknowledgement for the segment is outstanding? (A) urgent pointer (B) sliding window (C) sequence number (D) URG flag
Answer : (B)
Which of the following is not a task handled by a router? (A) A router forwards broadcasts over the network.
(B) A router can reroute traffic if the path of first choice is down but a second path is available.
(C) A router can interpret Layer 3 and often Layer 4 addressing.
(D) A router can connect dissimilar networks.
Answer : (A)
The IP connectionless protocol relies on what other protocol to guarantee delivery of data? (A) UDP (B) ICMP (C) TCP (D) ARP Answer : (C)
Answer : (C)
What command can be used on a Cisco router to view the routing table? (A) route print (B) netstat -r C) route (D) show ip route Answer : (D)
Answer : (D)
What parameter can be combined with the traceroute command to instruct it to use ICMP echo requests instead of UDP datagrams? (A) -n (B) -p (C) -I (D) -d Answer : (C)
Answer : (C)
What TCP field below allows the receiving node to determine whether a TCP segment is corrupted during transmission? (A) checksum (B) sliding window (C) acknowledgement number (D) TCP header length
Answer : (A)
What happens when a router receives a packet with a TTL of 0?
(A) The router attempts to forward the traffic on a local network
(B) The router drops the packet and sends an ICMP TTL expired message back to the host.
(C) The router resets the TTL to 128.
(D) The router marks the packet as corrupted and forwards it to the next hop.
Answer : (B)
In IPv6, what field is used to indicate what sequence of packets from one source to one or multiple destinations a packet belongs to? (A) traffic class (B) group ID (C) flow label D) traffic exchange
Answer : (C)
What IPv4 protocol handles multicasting for tasks such as videoconferencing or teleconferencing? (A) ICMP (B) ARP (C) TCP (D) IGMP
Answer : (D)
When viewing the routing table on a UNIX system, what flag indicates if a route is a usable route? (A) I (B) H (C) G (D) U
Answer : (D)
What routing protocol criteria is defined as the time it takes to recognize a best path change in the event of a network outage? (A) administrative distance detection (B) convergence time (C) overhead calculation (D) downed path detection
Answer : (B)
What type of routing protocol enables routers to communicate beyond neighboring routers, allowing each router to create a map of an entire network? (A) distance vector (B) link state (C) exterior gateway (D) map extension
Answer : (B)
The receiving host de-encapsulates the message at each layer in _______ order and then presents the payload to the receiving application.
Answer : reverse
The TCP ___________________ is performed before TCP transmits the actual data.
Answer : Three
way handshake
___’s lack of sophistication makes it more efficient than TCP.
Answer : UDP
ICMP (Internet Control Message Protocol) is a _______ layer core protocol that reports on the success or failure of data delivery.
Answer : Network
A _______ joins two or more networks and passes packets from one network to another.
Answer : router
Describe the difference between dynamic ARP table entries and static ARP table entries.
An ARP table can contain two types of entries: dynamic and static. Dynamic ARP table entries are created when a client makes an ARP request that could not be satisfied by data already in the ARP table. Static ARP table entries are those that someone has entered manually using the ARP utility.
Compare the three categories of routers.
The three categories of routers are as follows: • Interior routers direct data between networks within the same autonomous system. An autonomous system (AS) is a group of networks, often on the same domain, that are operated by the same organization. For example, Cengage, the company that published this book, might have several LANs that all fall under the cengage.com domain, with each LAN connected to the others by interior
routers. • Border routers (or gateway routers) connect an autonomous system with an outside network. For example, the router that connects a business with its ISP is a border router.
• Exterior routers direct data between autonomous systems. Routers that operate on the Internet backbone are considered exterior routers. An exterior router can also be a border or gateway router if it stands between an autonomous system and an outside network.
What is the difference between static and dynamic routing?
Static routing is a technique in which a network administrator configures a routing table to direct messages along specific paths between networks. Static routes are appropriate in certain situations, such as the static route between a small business and its ISP. However, static routes used to traverse several networks don’t account for occasional network congestion, failed connections, or device moves, and they require human intervention. Dynamic routing, on the other hand, automatically calculates the best path between two networks and accumulates this information in the routing table. If congestion or failures affect the network, a router using dynamic routing can detect the problems and reroute messages through a different path. By default, when a router is added to a network, dynamic routing ensures that the new router’s routing tables are updated.
List some examples of routing metrics that might be used to determine the best path for data.
Some examples of routing metrics used to determine the best path may include: Hop count (network segments crossed)
● Theoretical bandwidth and actual throughput on a potential path
● Delay, or latency, on a potential path, which results in slower performance
● Load, or the traffic or processing burden sustained by a router in the path
● MTU (maximum transmission unit), or the largest IP packet size in bytes allowable by routers in
● the path without fragmentation and excluding the frame size on the local network Routing cost, or a value assigned to a particular route as judged by the network administrator;
the● more desirable the path, the lower its cost Reliability of a potential path, based on historical performance
● The topology of a network
Which protocol’s header would a Layer 4 device read and process? A. IP B. TCP C. ARP D. HTTP
Answer: B. TCP
What number does a host use to identify the application involved in a transmission? A. IP address B. MAC address C. Port number D. Sequence number
Answer: C. Port number
What field in a TCP segment is used to determine if an arriving data unit exactly matches the data unit sent by the source? A. Source port B. Acknowledgment number C. Data D. Checksum
Answer: D. Checksum
At which OSI layer does IP operate? A. Application layer B. Transport layer C. Network layer D. Data Link layer
Answer: C. Network layer
Which OSI layer is responsible for directing data from one LAN to another? A. Transport layer B. Network layer C. Data Link layer D. Physical layer
Answer: B. Network layer
What kind of route is created when a network administrator configures a router to use a specific path between nodes? A. Trace route B. Static route C. Default route D. Best path
Answer: B. Static route
When a router can’t determine a path to a message’s destination, where does it send the message? A. Default gateway B. Default route C. Gateway of last resort D. Routing table
Answer: C. Gateway of last resort
A routing protocol’s reliability and priority are rated by what measurement? A. Routing table B. MTU C. Latency D. AD
Answer: D. AD
Which routing protocol does an exterior router use to collect data to build its routing tables? A. RIPv2 B. BGP C. OSPF D. IS-IS
10
Answer: B. BGP
When messages to a remote Web server are being lost for no apparent reason and you suspect
the problem might be a path MTU black hole, which TCP/IP utility can you use to diagnose
the problem?
A. netstat
B. traceroute
C. nbtstat
D. ping
Answer: D. ping
What three characteristics distinguish TCP from UDP?
Answer: TCP is connection-oriented, uses sequencing and checksums, and provides flow control.
What process is used to establish a TCP connection?
Answer: Three-way handshake
Which two protocols are essential to IPv4 networks, but whose functions are performed by
ICMPv6 on IPv6 networks?
Answer: IGMP, ARP
What is the difference between dynamic ARP table entries and static ARP table entries?
Answer: Dynamic ARP table entries are created when a client makes an ARP request, whereas
static ARP table entries are entered manually using the ARP utility.
What four functions do all routers perform?
Answer: 1. Connect dissimilar networks.
2. Interpret Layers 3 and 4 addressing and other
information.
3. Determine the best path for data to follow.
4. Reroute traffic if a primary path is
down but another path is available.
What database does a router consult before determining the most efficient path for delivering
a message?
Answer: Its routing table
Manually modifying a routing table can cause messages to get stuck hopping between a
limited number of routers. What is this problem called?
Answer: Routing loop
Give three examples of routing metrics used by routers to determine the best of various
available routing paths.
Answer: (Any three) Hop count, theoretical bandwidth, actual throughput, path latency (or
delay), path load, MTU, cost, reliability
List three interior gateway protocols (IGPs).
Answer: RIP/RIPv2, IS-IS, OSPF
What kind of Web site allows you to remotely collect network routing information back to
your actual location?
Answer: Looking glass site
