Consider the following statements: i. Address Resolution Protocol (ARP) provides a mapping from an IP address to the corresponding hardware (link-layer) address. ii. A single TCP segment from a sender S to a receiver R cannot carry both data from S to R and acknowledgement for a segment from R to S. Which one of the following is CORRECT? A. Both (i) and (ii) are TRUE B. (i) is TRUE and (ii) is FALSE C. (i) is FALSE and (ii) is TRUE D. Both (i) and (ii) are FALSE

GATE 2025 · Computer Networks · Arp · medium

Answer: B. (i) is TRUE and (ii) is FALSE

1. Evaluate Statement (i): ARP and IP-to-MAC mapping: ARP (Address Resolution Protocol) is defined in RFC 826 with the explicit purpose of mapping a network-layer (IP) address to a link-layer (hardware/MAC) address. A host broadcasts an ARP request asking 'Who has IP address X?' and the host with that IP responds with its MAC address. Statement (i) is exactly correct and is TRUE.
2. Evaluate Statement (ii): TCP piggybacking: Statement (ii) claims a TCP segment from S to R cannot carry both data (S to R) AND an acknowledgment (for data from R to S). This is FALSE. TCP uses piggybacking: the TCP header includes both a Sequence Number field (carrying data from S to R) and an Acknowledgment Number field (acknowledging data received from R). Both fields are present in every TCP segment, so one segment absolutely can carry data in one direction while simultaneously acknowledging data from the other direction. This is standard, efficient TCP behavior.
3. Determine correct answer option: Statement (i) = TRUE, Statement (ii) = FALSE. The matching option is: '(i) is TRUE and (ii) is FALSE' = Option B.