How would you verify that a DNS response matches a particular query ID?

• A. Check the dns.id in the response against the corresponding query’s transaction ID and ensure the answer section matches the query name
• B. Compare the IP addresses
• C. Compare the DNS TTL
• D. Check the MAC address in the response

Answer: (A)

DNS responses include a 16-bit transaction ID in the header. The response must carry the same ID as the query, so comparing the response’s id to the query’s id confirms this is the reply to your request. In addition, you should verify that the domain name in the response matches the queried name (the question section or the answer’s name field should reflect the same domain). This dual check—matching the transaction ID and the requested name—ensures the response corresponds to your specific query and contains the correct data. Other pieces like IP addresses, TTL values, or MAC addresses don’t reliably link a response to a particular query, so they’re not used for this verification.