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) prehensive error and flow control.
B) limited error control, but no flow control.
C) prehensive 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.
计算机学院排名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 ma*imum
C) decreases sharply; its minimum
D) decreases sharply; its ma*imum
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) e*cluding the header
C) e*cluding 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 _______.
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