This set of Computer Networks Questions and Answers for Aptitude test focuses on “Datagram Networks”.
1. Datagram switching is done at which layer of OSI model?
a) Network layer
b) Physical layer
c) Application layer
d) Transport layer
Explanation: Datagram switching is normally done at network layer. In datagram switching, the datagram stream need not be in order as each datagram can take different routes to the destination.
2. Packets in datagram switching are referred to as ________
Explanation: As the name suggests, in datagram switching packets are called as datagram. Each datagram/packet is treated as an individual entity and routed independently through the network.
3. Datagram networks mainly refers to _________
a) Connection oriented networks
b) Connection less networks
c) Telephone networks
Explanation: The switch does not keep the information about the connection state, hence it is connection less. There is no need for establishing a handshake to begin the transmission in such networks.
4. Datagrams are routed to their destinations with the help of ________
a) Switch table
b) Segments table
c) Datagram table
d) Routing table
Explanation: Routing table is used to route the packets to their destinations. The packet/datagram header contains the destination header for the whole journey to source to the destination through the routers.
5. The main contents of the routing table in datagram networks are ___________
a) Source and Destination address
b) Destination address and Output port
c) Source address and Output port
d) Input port and Output port
Explanation: Routing table contains destination address and output port to route the packets to their destinations. The port address specifies the particular application that the packet has to be forwarded to after it has reached the destination.
6. Which of the following remains same in the header of the packet in a datagram network during the entire journey of the packet?
a) Destination address
b) Source address
Explanation: Destination address remains same in the header during the entire journey of the packet. There is no pre-decided route for the packets so each datagram/packet is treated as an individual entity and routed independently through the network.
7. Which of the following is true with respect to the delay in datagram networks?
a) Delay is greater than in a virtual circuit network
b) Each packet may experience a wait at a switch
c) Delay is not uniform for the packets of a message
d) All of the mentioned
Explanation: The delay of each packet in a datagram network is different as each packet might take a different route to the destination. The delay includes the propagation delay and the processing delay that is induced at each stop/switch that the packet encounters in its journey.
8. During datagram switching, the packets are placed in __________ to wait until the given transmission line becomes available.
d) Routing table
Explanation: When there are too many packets to be transmitted and the transmission line gets blocked while transmitting some packets, the remaining packets are stored in queue during delay and are served as first in first out. The delay is called as queuing delay.
9. The probability of the error in a transmitted block _________ with the length of the block
a) Remains same
d) Is not proportional
Explanation: Probability of the error in a transmitted block increases with the length of the block. Hence, the blocks should be as short as possible for ideal transmission with low possibility of an error.
10. Which of the following is false with respect to the datagram networks?
a) Number of flows of packets are not limited
b) Packets may not be in order at the destination
c) Path is not reserved
d) Delay is the same for all packets in a flow
Explanation: The delay of each packet in a datagram network is different as each packet might take a different route to the destination. This happens because there is no pre-decided route for the packets.
Sanfoundry Global Education & Learning Series – Computer Networks.
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