Which statement about the DNS protocol is true?

Which statement about the DNS protocol is true?

• A. DNS involves query and reply messages with the same format (port 53)
• B. DNS transfers files between hosts
• C. DNS directly routes traffic between networks
• D. DNS assigns IP addresses

Answer: (A)

DNS works by clients sending questions to a DNS server and receiving answers in return, all using the same DNS message format defined for queries and responses. These messages are carried over UDP port 53, with servers listening on that port and replies typically coming from port 53 back to the client’s ephemeral port. If a response is larger than UDP can handle, DNS can switch to TCP on port 53 to complete the transfer, but it still uses the same DNS message structure. This makes the statement true because the query and the reply share the same DNS message format and the communication typically uses port 53. The other statements don’t fit how DNS functions: DNS is not used for transferring files between hosts, it does not route traffic between networks, and it does not assign IP addresses (that’s the role of DHCP or manual configuration).

DNS works by clients sending questions to a DNS server and receiving answers in return, all using the same DNS message format defined for queries and responses. These messages are carried over UDP port 53, with servers listening on that port and replies typically coming from port 53 back to the client’s ephemeral port. If a response is larger than UDP can handle, DNS can switch to TCP on port 53 to complete the transfer, but it still uses the same DNS message structure.

This makes the statement true because the query and the reply share the same DNS message format and the communication typically uses port 53. The other statements don’t fit how DNS functions: DNS is not used for transferring files between hosts, it does not route traffic between networks, and it does not assign IP addresses (that’s the role of DHCP or manual configuration).