A packet capture shows a UDP datagram with source port 53, destination port 5353, length 45, and checksum 0x1234. What is the purpose of the checksum field in this UDP header?

To ensure the packet is delivered in order.

To indicate the length of the UDP payload.

To authenticate the source of the packet.

To detect corruption in the UDP header and payload during transmission.

An analyst is reviewing a packet capture and sees a UDP packet with source port 53 and destination port 5353. The UDP length field is 45 bytes. What type of traffic is this most likely to be?

A TFTP data transfer from a TFTP server.

A DNS response from a DNS server to a client using mDNS.

An NTP time synchronization packet from an NTP server.

A DHCP offer from a DHCP server to a client.

A network engineer is troubleshooting a connectivity issue. A packet capture shows an ICMP Time Exceeded message being sent back to the source. Which condition most likely triggered this ICMP message?

The destination host rejected the packet because the port was closed.

The packet was fragmented and could not be reassembled within the timeout period.

The source host received an ICMP Echo Reply from an unexpected address.

A router discarded a packet because its TTL field reached zero.

A network analyst is investigating a slow network connection. The analyst sees ICMP Redirect messages in the packet capture. What is the purpose of an ICMP Redirect message?

To inform a host that a better route exists to a destination.

To notify a host that its packets are being dropped due to congestion.

To request the host to slow down its transmission rate.

To indicate that the destination host is unreachable.

GIAC Certified Intrusion Analyst

Domain 1Objective 5

UDP and ICMP 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 33 practice questions to prepare you well beyond it. (estimate)

33questions here

7free pages

6concepts

Questions 11–15

11application · medium
A packet capture shows a UDP datagram with source port 53, destination port 5353, length 45, and checksum 0x1234. What is the purpose of the checksum field in this UDP header?
Select an answer first
12application · medium
An analyst is reviewing a packet capture and sees a UDP packet with source port 53 and destination port 5353. The UDP length field is 45 bytes. What type of traffic is this most likely to be?
Select an answer first
13application · medium
A network engineer is troubleshooting a connectivity issue. A packet capture shows an ICMP Time Exceeded message being sent back to the source. Which condition most likely triggered this ICMP message?
Select an answer first
14application · medium
A network analyst is investigating a slow network connection. The analyst sees ICMP Redirect messages in the packet capture. What is the purpose of an ICMP Redirect message?
Select an answer first
15foundation · easy
Which ICMP message type would a router send when it cannot forward a packet because the destination network is unreachable?
Select an answer first

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