Chapter 4 Network Layer
1.
Packetizing at the network layer involves A) Encapsulating the payload at the source
B) Adds a header that contains the source and destination information C) Decapsulating the payload at the destination D) All of the choices are correct 2.
Routers in the path are not allowed to ___________________________. A) fragment the packet they receive B) decapsulate the packet
C) change source or destination address D) All of the choices are correct 3.
The network layer in the Internet provides _________________. A) comprehensive error and flow control. B) limited error control, but no flow control.
C) comprehensive error control but limited flow control. D) All of the choices are correct 4.
In a virtual-circuit approach, the forwarding decision is based on the value of the _____________ field in the packet header.
A) source address B) destination address C) label
D) None of the choices are correct 5.
In a datagram approach, the forwarding decision is based on the value of the _____________ field in the packet header. A) source address B) destination address C) label
D) None of the choices are correct 6.
The performance of a network can be measured in terms of ________. A) delay B) throughput C) packet loss
D) all of the choices are correct 7.
Transmission delay (time) is the ratio of ______________________. A) transmission rate to packet length B) transmission rate to distance C) packet length to transmission rate D) processing time to transmission rate
8.
Propagation delay (time) is the ratio of ______________________. A) transmission rate to propagation speed B) propagation speed to distance C) packet length to propagation speed D) distance to propagation speed 9.
When the load in the network reaches the network capacity, the packet delay ___________ and the network throughput reaches ______________. A) increases sharply; its minimum B) increases sharply; its maximum C) decreases sharply; its minimum D) decreases sharply; its maximum 10.
In open-loop congestion control, policies are applied ____________________. A) to prevent congestion before it happens B) to alleviate congestion after it happens
C) to either prevent congestion before it happens or to alleviate congestion after it happens
D) None of the choices are correct 11.
The __________________ technique is one of the open-loop congestion policy
A) backpressure B) choke packet C) implicit signaling
D) None of the choices are correct 12.
The __________________ technique is one of the close-loop congestion policy A) acknowledgment policy B) choke packet C) discarding policy
D) None of the choices are correct 13.
IP is a _________ protocol. A) connection-oriented unreliable B) connection-oriented reliable C) connectionless unreliable D) connectionless reliable 14.
An HLEN value of decimal 10 means _______. A) there are 10 bytes of options B) there are 10 bytes in the header C) there are 40 bytes of options D) there are 40 bytes in the header
15.
If the fragment offset has a value of 100, it means that _______. A) the datagram has not been fragmented B) the datagram is 100 bytes in size
C) the first byte of the datagram is byte 800 D) None of the choices are correct 16.
What is needed to determine the number of the last byte of a fragment? A) offset number B) total length
C) both offset number and the total length D) None of the choices are correct 17.
The IP header size is _______ bytes long. A) 20 to 60 B) 20 C) 60
D) None of the choices are correct 18.
Packets in the IP layer are called _________. A) segments
B) datagrams C) frames
D) None of the choices are correct 19.
The total length field defines the total length of the datagram _________. A) including the header B) excluding the header C) excluding the option length D) None of the choices are correct 20.
When a datagram is encapsulated in a frame, the total size of the datagram must be less than the _______. A) MUT B) MAT C) MTU
D) None of the choices are correct 21.
An IPv4 address is normally represented in base ____ in dotted-decimal notation. A) 16 B) 256 C) 10
D) None of the choices are correct
22.
In classful addressing, the IPv4 address space is divided into _______ classes. A) 3 B) 4 C) 5
D) None of the choices are correct 23.
The number of addresses assigned to an organization in classless addressing _______. A) can be any number B) must be a multiple of 256 C) must be a power of 2
D) None of the choices are correct 24.
The first address assigned to an organization in classless addressing _______. A) must be evenly divisible by the number of addresses in the organization B) must be divisible by 128
C) must belong to one of the A, B, or C classes D) None of the choices are correct 25.
In subnetting, the number of addresses in each subnet must _______. A) be a power of 2 B) be a multiple of 128
C) be divisible by 128
D) None of the choices are correct 26.
What is the default prefix length for class A in CIDR notation? A) 9 B) 8 C) 16
D) None of the choices are correct 27.
What is the default prefix length for class B in CIDR notation? A) 9 B) 8 C) 16
D) None of the choices are correct 28.
What is the default prefix length for class C in CIDR notation? A) 24 B) 8 C) 16
D) None of the choices are correct 29.
DHCP is a (an) ___________ layer protocol. A) application B) transport C) network D) data-link 30.
In DHCP, the client uses ________ port and the server uses _________ port. A) an ephemeral; a well-known B) a well-known; a well-known C) a well-known; an ephemeral D) None of the choices are correct 31.
DHCP uses the services of _______. A) UDP B) TCP C) IP
D) None of the choices are correct 32.
_________ allows a site to use a set of private addresses for internal communication and a set of global Internet addresses for communication with the rest of the world. A) DHCP B) NAT C) IMCP
D) None of the choices are correct 33.
The idea of address aggregation was designed to alleviate the increase in routing table entries when using ________ addressing. A) classful B) classless
C) classful or classless
D) None of the choices are correct 34.
The use of hierarchy in routing tables can ________ the size of the routing tables. A) reduce B) increase
C) neither reduce nor increase D) None of the choices are correct 35.
ICMP is a (an) _________ layer protocol.
A) application-layer protocol that helps TCP/IP at the network layer B) transport-layer protocol that helps TCP/IP at the network layer C) network-layer protocol.
D) data-link layer protocol that helps TCP/IP at the network layer 36.
Which of the following is true about ICMP messages?
A) An ICMP error message may be generated for an ICMP error message. B) An ICMP error message may be generated for a fragmented datagram. C) An ICMP error message may be generated for a multicast datagram. D) None of the choices are correct 37.
Routing inside an autonomous system is referred to as ________ routing. A) interdomain B) intradomain C) out-of-domain
D) None of the choices are correct 38.
Routing between autonomous systems is referred to as ______ routing. A) interdomain routing B) intradomain routing C) out-of-domain
D) None of the choices are correct 39.
In _______ routing, the least cost route between any two nodes is the route with the minimum distance. A) path vector B) distance vector C) link state
D) None of the choices are correct
40.
In ________, each node maintains a vector (table) of minimum distances to every node. A) path vector B) distance vector C) link state
D) None of the choices are correct 41.
In distance vector routing, each node periodically shares its routing table with _________ and whenever there is a change. A) every other node B) its immediate neighbors C) one neighbor
D) None of the choices are correct 42.
The Routing Information Protocol (RIP) is an intradomain routing based on _________ routing.
A) distance vector B) link state C) path vector
D) None of the choices are correct 43.
The metric used by _______ is the hop count.
A) OSPF B) RIP C) BGP
D) None of the choices are correct 44.
In RIP, the ________ timer controls the advertising of regular update messages. A) garbage collection B) expiration C) periodic
D) None of the choices are correct 45.
In RIP, the ________ timer is used to purge invalid routes from the table. A) garbage collection B) expiration C) periodic
D) None of the choices are correct 46.
In RIP, the ________ timer controls the validity of the route. A) garbage collection B) expiration C) periodic
D) None of the choices are correct
47.
RIP uses the services of _______. A) TCP B) UDP C) IP
D) None of the choices are correct 48.
The _________ routing uses the Dijkstra algorithm to build a routing table. A) distance vector B) link state C) path vector
D) None of the choices are correct 49.
The Open Shortest Path First (OSPF) protocol is an intradomain routing protocol based on _______ routing. A) distance vector B) link state C) path vector
D) None of the choices are correct 50.
The _______ protocol allows the administrator to assign a cost, called the metric, to each route.
A) OSPF B) RIP C) BGP
D) None of the choices are correct 51.
In OSPF, a ________ link connects two routers without any other host or router in between.
A) point-to-point B) transient C) stub
D) None of the choices are correct 52.
In OSPF, a _______ link is a network with several routers attached to it. A) point-to-point B) transient C) stub
D) None of the choices are correct 53.
In OSPF, a ________ link is a network connected to only one router. A) point-to-point B) transient C) stub
D) None of the choices are correct
54.
In OSPF, a ________ defines the links of a network. A) network link B) router link
C) summary link to network D) None of the choices are correct 55.
___________ is an interdomain routing protocol using path vector routing. A) BGP B) RIP C) OSPF
D) None of the choices are correct 56.
A one-to-all communication between one source and all hosts on a network is classified as a _______ communication. A) unicast B) multicast C) broadcast
D) None of the choices are correct 57.
A one-to-many communication between one source and a specific group of hosts is classified as a _______ communication.
A) unicast B) multicast C) broadcast
D) None of the choices are correct 58.
A one-to-one communication between one source and one destination is classified as a _______ communication. A) unicast B) multicast C) broadcast
D) None of the choices are correct 59.
In ______, the router forwards the received packet through only one of its interfaces. A) unicasting B) multicasting C) broadcasting
D) None of the choices are correct 60.
In multicast routing, each involved router needs to construct a ________ path tree for each group. A) average B) longest C) shortest
D) None of the choices are correct 61.
In the _______ tree approach to multicasting, each router needs to create a separate tree for each source-group. A) group-shared B) source-based C) destination-based
D) None of the choices are correct 62.
The Multicast Open Shortest Path First (MOSPF) routing uses the _______ tree approach. A) source-based B) group-shared C) destination-based
D) None of the choices are correct 63.
The Multicast Open Shortest Path First (MOSPF) protocol is an extension of the OSPF protocol that uses multicast routing to create source-based trees. The protocol is based on _______ routing. A) distance vector B) link state C) path vector
D) None of the choices are correct 64.
In RPF, a router forwards only the copy that has traveled the _______ path from the source to the router. A) shortest B) longest C) average
D) None of the choices are correct 65.
RPF eliminates the ________ in the flooding process. A) forwarding B) backwarding C) flooding
D) None of the choices are correct 66.
RPB creates a shortest path _______ tree from the source to each destination. A) unicast B) multicast C) broadcast
D) None of the choices are correct 67.
RPB guarantees that each destination receives _________ of the packet. A) only one copy B) no copies C) multiple copies
D) None of the choices are correct 68.
In ________, the multicast packet must reach only those networks that have active members for that particular group. A) RPF B) RPB C) RPM
D) None of the choices are correct 69.
_______ adds pruning and grafting to _______ to create a multicast shortest path tree that supports dynamic membership changes. A) RPM; RPB B) RPB; RPM C) RPF; RPM
D) None of the choices are correct 70.
__________ is an implementation of multicast distance vector routing. It is a source-based routing protocol, based on RIP. A) MOSPF B) DVMRP C) CBT
D) None of the choices are correct 71.
DVMRP is a ________ routing protocol, based on RIP. A) source-based B) group-shared C) destination-based
D) None of the choices are correct 72.
Pruning and grafting are strategies used in _______. A) RPF B) RPB C) RPM
D) None of the choices are correct 73.
PIM-DM is used when the number of routers with attached members is ______ relative to the number of routers in the internet. A) large B) small C) moderate
D) None of the choices are correct 74.
PIM-SM is used when the number of routers with attached members is ______ relative to the number of routers in the internet. A) large B) small
C) moderate
D) None of the choices are correct 75.
An IPv6 address is _________ bits long. A) 32 B) 64 C) 128 D) 256 76.
An IPv6 address consists of ________ bytes (octets); A) 4 B) 8 C) 16
D) None of the choices are correct 77.
In hexadecimal colon notation, a 128-bit address is divided into _______ sections, each _____ hexadecimal digits in length. A) 8; 2 B) 8; 3 C) 8; 4
D) None of the choices are correct 78.
An IPv6 address can have up to __________ hexadecimal digits. A) 16 B) 32 C) 8
D) None of the choices are correct 79.
In IPv6, the _______ field in the base header restricts the lifetime of a datagram. A) version B) priority C) hop limit
D) None of the choices are correct 80.
The _________ in IPv6 is designed to provide special handling for a particular flow of data. A) flow label B) next header C) hop limit
D) None of the choices are correct 81.
When two computers using IPv6 want to communicate but the packet must pass through an IPv4 region, which transition strategy should be used? A) tunneling
B) header translation
C) either tunneling or header translation D) None of the choices are correct 82.
When the majority of the Internet has moved to the IPv6 but some still use IPv4, which transition strategy should be used? A) tunneling
B) header translation
C) either tunneling or header translation D) None of the choices are correct 83.
The protocols __________________________ in version 4 are combined into one single protocol, ICMPv6. A) ARP and IGMP B) ICMP and IGMP C) ICMP, ARP, and IGMP
D) None of the choices are correct
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计算机网络教程自顶向下方法选择题及答案chapt4network
