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210-255 · Question #110
210-255 Question #110: Real Exam Question with Answer & Explanation
The correct answer is B: source IP address of the packet. The IPv4 header contains source and destination IP addresses at the network layer, while port information belongs to the transport layer headers (TCP/UDP) and is not present in the IPv4 header itself.
Question
Which two useful pieces of information can be collected from the IPv4 protocol header? (Choose two.)
Options
- AUDP port which the traffic is destined
- Bsource IP address of the packet
- CUDP port from which the traffic is sourced
- DTCP port from which the traffic was source
- Edestination IP address of the packet
Explanation
The IPv4 header contains source and destination IP addresses at the network layer, while port information belongs to the transport layer headers (TCP/UDP) and is not present in the IPv4 header itself.
Common mistakes.
- A. UDP destination port is a field in the UDP header at Layer 4, not in the IPv4 header at Layer 3.
- C. UDP source port is a field in the UDP header at Layer 4, not in the IPv4 header at Layer 3.
- D. TCP source port is a field in the TCP header at Layer 4, not in the IPv4 header at Layer 3.
Concept tested. IPv4 header field identification
Reference. https://www.rfc-editor.org/rfc/rfc791
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