CS 6250 Practice Exam Questions and Answers with
Rationales Latest Version Top Rated A+
1. Which layer of the TCP/IP model is primarily responsible for end-to-end
reliable delivery?
A. Application
B. Transport
C. Internet
D. Link
Answer: B. Transport
Rationale: The transport layer provides end-to-end communication between
applications. TCP operates at this layer and provides reliability, sequencing,
acknowledgments, retransmission, and flow/congestion control.
2. What is the primary purpose of an IP routing table?
A. Store DNS records
B. Determine how packets should be forwarded toward their destinations
C. Encrypt network traffic
D. Establish TCP connections
Answer: B. Determine how packets should be forwarded toward their
destinations
Rationale: Routers examine destination IP addresses and consult their routing
tables to select the appropriate next hop or outgoing interface.
3. Which protocol is connection-oriented?
,A. UDP
B. IP
C. TCP
D. ARP
Answer: C. TCP
Rationale: TCP establishes a logical connection using a three-way handshake
before transferring application data. UDP is connectionless and does not perform
this handshake.
4. What is the main purpose of the TCP three-way handshake?
A. Resolve a domain name
B. Establish communication parameters and synchronize sequence numbers
C. Encrypt the connection
D. Determine the shortest network path
Answer: B. Establish communication parameters and synchronize sequence
numbers
Rationale: SYN, SYN-ACK, and ACK messages establish the TCP connection
and synchronize initial sequence numbers between the endpoints.
5. Which protocol translates domain names such as example.com into IP
addresses?
A. DHCP
B. DNS
C. ARP
D. ICMP
Answer: B. DNS
Rationale: The Domain Name System (DNS) provides name resolution,
translating human-readable domain names into IP addresses and other resource
records.
,6. A router receives a packet whose destination matches multiple routing-table
entries. Which principle generally determines the selected route?
A. Shortest hostname
B. Longest prefix match
C. Lowest source-port number
D. Largest packet size
Answer: B. Longest prefix match
Rationale: Routers generally select the routing-table entry with the most specific
matching network prefix. For example, a /24 route is preferred over a matching
/16 route.
7. Which routing protocol is primarily used to exchange routing information
between autonomous systems on the Internet?
A. RIP
B. OSPF
C. BGP
D. ARP
Answer: C. BGP
Rationale: Border Gateway Protocol (BGP) is the principal interdomain routing
protocol used to exchange reachability information between autonomous systems.
8. What is the major difference between TCP and UDP?
A. TCP uses IP while UDP does not
B. TCP provides connection-oriented reliable delivery, while UDP provides
connectionless best-effort delivery
C. UDP supports only IPv6
D. TCP cannot transmit application data
, Answer: B. TCP provides connection-oriented reliable delivery, while UDP
provides connectionless best-effort delivery
Rationale: TCP includes mechanisms such as acknowledgments, retransmissions,
sequencing, and congestion control. UDP has considerably less protocol overhead
and does not inherently guarantee delivery.
9. Which mechanism allows TCP to regulate how much data a sender can
transmit before receiving acknowledgments?
A. DNS caching
B. Sliding window
C. ARP resolution
D. IP fragmentation
Answer: B. Sliding window
Rationale: TCP uses a window-based mechanism to control the amount of
unacknowledged data that can be in flight. The effective sending window is
influenced by both receiver flow control and congestion control.
10. What problem does TCP congestion control primarily attempt to address?
A. Incorrect DNS names
B. Network overload caused by excessive traffic
C. Physical cable damage
D. MAC-address duplication
Answer: B. Network overload caused by excessive traffic
Rationale: TCP congestion control attempts to prevent senders from injecting
more traffic into the network than the network can handle, reducing packet loss
and congestion collapse.
Rationales Latest Version Top Rated A+
1. Which layer of the TCP/IP model is primarily responsible for end-to-end
reliable delivery?
A. Application
B. Transport
C. Internet
D. Link
Answer: B. Transport
Rationale: The transport layer provides end-to-end communication between
applications. TCP operates at this layer and provides reliability, sequencing,
acknowledgments, retransmission, and flow/congestion control.
2. What is the primary purpose of an IP routing table?
A. Store DNS records
B. Determine how packets should be forwarded toward their destinations
C. Encrypt network traffic
D. Establish TCP connections
Answer: B. Determine how packets should be forwarded toward their
destinations
Rationale: Routers examine destination IP addresses and consult their routing
tables to select the appropriate next hop or outgoing interface.
3. Which protocol is connection-oriented?
,A. UDP
B. IP
C. TCP
D. ARP
Answer: C. TCP
Rationale: TCP establishes a logical connection using a three-way handshake
before transferring application data. UDP is connectionless and does not perform
this handshake.
4. What is the main purpose of the TCP three-way handshake?
A. Resolve a domain name
B. Establish communication parameters and synchronize sequence numbers
C. Encrypt the connection
D. Determine the shortest network path
Answer: B. Establish communication parameters and synchronize sequence
numbers
Rationale: SYN, SYN-ACK, and ACK messages establish the TCP connection
and synchronize initial sequence numbers between the endpoints.
5. Which protocol translates domain names such as example.com into IP
addresses?
A. DHCP
B. DNS
C. ARP
D. ICMP
Answer: B. DNS
Rationale: The Domain Name System (DNS) provides name resolution,
translating human-readable domain names into IP addresses and other resource
records.
,6. A router receives a packet whose destination matches multiple routing-table
entries. Which principle generally determines the selected route?
A. Shortest hostname
B. Longest prefix match
C. Lowest source-port number
D. Largest packet size
Answer: B. Longest prefix match
Rationale: Routers generally select the routing-table entry with the most specific
matching network prefix. For example, a /24 route is preferred over a matching
/16 route.
7. Which routing protocol is primarily used to exchange routing information
between autonomous systems on the Internet?
A. RIP
B. OSPF
C. BGP
D. ARP
Answer: C. BGP
Rationale: Border Gateway Protocol (BGP) is the principal interdomain routing
protocol used to exchange reachability information between autonomous systems.
8. What is the major difference between TCP and UDP?
A. TCP uses IP while UDP does not
B. TCP provides connection-oriented reliable delivery, while UDP provides
connectionless best-effort delivery
C. UDP supports only IPv6
D. TCP cannot transmit application data
, Answer: B. TCP provides connection-oriented reliable delivery, while UDP
provides connectionless best-effort delivery
Rationale: TCP includes mechanisms such as acknowledgments, retransmissions,
sequencing, and congestion control. UDP has considerably less protocol overhead
and does not inherently guarantee delivery.
9. Which mechanism allows TCP to regulate how much data a sender can
transmit before receiving acknowledgments?
A. DNS caching
B. Sliding window
C. ARP resolution
D. IP fragmentation
Answer: B. Sliding window
Rationale: TCP uses a window-based mechanism to control the amount of
unacknowledged data that can be in flight. The effective sending window is
influenced by both receiver flow control and congestion control.
10. What problem does TCP congestion control primarily attempt to address?
A. Incorrect DNS names
B. Network overload caused by excessive traffic
C. Physical cable damage
D. MAC-address duplication
Answer: B. Network overload caused by excessive traffic
Rationale: TCP congestion control attempts to prevent senders from injecting
more traffic into the network than the network can handle, reducing packet loss
and congestion collapse.
