What is the purpose of the Frame Check Sequence (FCS) field in an Ethernet frame?

To identify the upper-layer protocol

To synchronize the receiver with the incoming bit stream

To detect errors in the frame during transmission

To specify the source and destination MAC addresses

A network administrator is troubleshooting a problem where a host can ping a server but cannot establish a TCP connection to it. The host and server are on different subnets separated by a router. The administrator suspects an MTU issue. Which of the following is the most likely cause?

The server's TCP stack is rejecting packets with the DF bit set.

The router is fragmenting TCP packets, but the server cannot reassemble them.

The host's TCP window size is too small, preventing the connection from being established.

The router is dropping large TCP packets because the DF bit is set and ICMP Packet Too Big messages are blocked.

A network engineer is explaining to a colleague how a packet is processed when it arrives at a router. The router receives an Ethernet frame, strips the link-layer header, examines the IP header, and then forwards the packet out another interface. Which of the following best describes the process?

The router decapsulates the IP packet from the frame, makes a routing decision, and re-encapsulates it into a new frame for the next hop.

The router modifies the IP header's source and destination IP addresses before forwarding.

The router strips the IP header and forwards the TCP segment directly to the destination.

The router forwards the original Ethernet frame unchanged to the next hop.

A developer is designing a real-time voice application that must minimize latency and can tolerate occasional packet loss. The application runs over UDP. Which characteristic of UDP makes it suitable for this use case?

UDP guarantees in-order delivery of packets.

UDP has a minimal header and no connection establishment, reducing overhead and delay.

UDP includes flow control and congestion avoidance mechanisms.

UDP provides reliable delivery with retransmission of lost packets.

What is the primary function of the link layer in the TCP/IP model?

To provide reliable end-to-end delivery with acknowledgments

To route packets between different networks

To encapsulate IP packets into frames and handle physical addressing

To establish and manage sessions between applications

GIAC Certified Intrusion Analyst

Domain 1Objective 1

Concepts of TCP/IP and the Link Layer GCIA Practice Questions (Page 3)

Part of the Network Fundamentals domain, which makes up ~35% of our current practice bank. GIAC (SANS) does not publish an official question count, but from its 240-minute exam (~95–160 total, ~33–56 in this domain), expect 7–11 from this objective — we provide 42 practice questions to prepare you well beyond it. (estimate)

42questions here

9free pages

12concepts

Questions 11–15

11foundation · easy
What is the purpose of the Frame Check Sequence (FCS) field in an Ethernet frame?
Select an answer first
12expert · hard
A network administrator is troubleshooting a problem where a host can ping a server but cannot establish a TCP connection to it. The host and server are on different subnets separated by a router. The administrator suspects an MTU issue. Which of the following is the most likely cause?
Select an answer first
13expert · hard
A network engineer is explaining to a colleague how a packet is processed when it arrives at a router. The router receives an Ethernet frame, strips the link-layer header, examines the IP header, and then forwards the packet out another interface. Which of the following best describes the process?
Select an answer first
14application · medium
A developer is designing a real-time voice application that must minimize latency and can tolerate occasional packet loss. The application runs over UDP. Which characteristic of UDP makes it suitable for this use case?
Select an answer first
15foundation · easy
What is the primary function of the link layer in the TCP/IP model?
Select an answer first

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