Computer Networks Exam 2025 Questions and
Answers
Datagram - ✔✔the name of a network-layer packet
What is the difference between a router and a link-layer switch? - ✔✔Router uses IP (layer
3) address of the packet to forward it.
Switch uses MAC (layer 2) address of packet to forward it.
Two most important network-layer functions in a datagram network? - ✔✔Forwarding and
routing
Forwarding - ✔✔process of moving the packet that arrives at the input link of the router to a
correct output link. Done by using forwarding tables.
Routing - ✔✔route in which the packet flows from sender to receiver, calculated by routing
algorithm. Determines end-to-end paths that packet takes
Important network-layer functions in a virtual-circuit network - ✔✔Forwarding, routing,
connection setup
Connection setup - ✔✔three-way handshake is required before data flows from source to
destination. Routers along the chosen path handshake with each other to set up connection
What are some services that network layer provides to a single packet? - ✔✔Guaranteed
delivery, guaranteed delivery with bounded delay
Applications that would benefit from ATM's CBR service model - ✔✔Telephone companies,
audio/video traffic, live multimedia apps
, What are the three types of switching fabrics? Which can send multiple packets across the
fabric in parallel? - ✔✔Via memory, via bus, via interconnected network.
Switching via interconnected network, allows packets from different input ports to the same
output port.
Do routers have IP addresses? How many? - ✔✔Every router has an IP address for each
interface.
What is the 32-bit binary equivalent of the IP address 223.1.3.27? - ✔✔Each decimal number
represents a byte (8 bits).
11011111 00000001 00000011 00011011
What is DHCP? - ✔✔Dynamic Host Configuration Protocol. Allows the host in obtaining the
IP address automatically. Client-server protocol.
When one host sends a TCP segment encapsulated in an IP datagram, how does the receiving
host network layer know it should pass the segment to TCP rather than UDP or something else?
- ✔✔The IP datagram consts of an 8-bit field called Protocol, which gives info about which
transport layer protocol the segment is to be passed to.
What are the differences/similarities between the IPv4 and IPv6 headers? - ✔✔IPv6 consists
of minimum number of fields, rather than a lot of optional fields.
IPv6 has a FIXED header size (40 bytes), IPv4 header is TYPICALLY 20-bytes.
IPv6 src/dest address: 128 bits.
IPv4 src/dest address: 32 bits.
Compare/contrast link-state and distance-vector routing algorithms - ✔✔Both find best path
from src router to dest router. Both compute least-cost path.
Answers
Datagram - ✔✔the name of a network-layer packet
What is the difference between a router and a link-layer switch? - ✔✔Router uses IP (layer
3) address of the packet to forward it.
Switch uses MAC (layer 2) address of packet to forward it.
Two most important network-layer functions in a datagram network? - ✔✔Forwarding and
routing
Forwarding - ✔✔process of moving the packet that arrives at the input link of the router to a
correct output link. Done by using forwarding tables.
Routing - ✔✔route in which the packet flows from sender to receiver, calculated by routing
algorithm. Determines end-to-end paths that packet takes
Important network-layer functions in a virtual-circuit network - ✔✔Forwarding, routing,
connection setup
Connection setup - ✔✔three-way handshake is required before data flows from source to
destination. Routers along the chosen path handshake with each other to set up connection
What are some services that network layer provides to a single packet? - ✔✔Guaranteed
delivery, guaranteed delivery with bounded delay
Applications that would benefit from ATM's CBR service model - ✔✔Telephone companies,
audio/video traffic, live multimedia apps
, What are the three types of switching fabrics? Which can send multiple packets across the
fabric in parallel? - ✔✔Via memory, via bus, via interconnected network.
Switching via interconnected network, allows packets from different input ports to the same
output port.
Do routers have IP addresses? How many? - ✔✔Every router has an IP address for each
interface.
What is the 32-bit binary equivalent of the IP address 223.1.3.27? - ✔✔Each decimal number
represents a byte (8 bits).
11011111 00000001 00000011 00011011
What is DHCP? - ✔✔Dynamic Host Configuration Protocol. Allows the host in obtaining the
IP address automatically. Client-server protocol.
When one host sends a TCP segment encapsulated in an IP datagram, how does the receiving
host network layer know it should pass the segment to TCP rather than UDP or something else?
- ✔✔The IP datagram consts of an 8-bit field called Protocol, which gives info about which
transport layer protocol the segment is to be passed to.
What are the differences/similarities between the IPv4 and IPv6 headers? - ✔✔IPv6 consists
of minimum number of fields, rather than a lot of optional fields.
IPv6 has a FIXED header size (40 bytes), IPv4 header is TYPICALLY 20-bytes.
IPv6 src/dest address: 128 bits.
IPv4 src/dest address: 32 bits.
Compare/contrast link-state and distance-vector routing algorithms - ✔✔Both find best path
from src router to dest router. Both compute least-cost path.
