CyberCertPrepNetwork FundamentalsOSI & TCP/IP ModelsEASYFree question
Which of the following is a characteristic of UDP that makes it suitable for DNS name resolution queries?
- A.UDP provides guaranteed delivery, ensuring DNS responses always arrive; half-open connections are closed by the data link layer after three beacon intervals. MAC addresses are assigned by DHCP alongside the IP address at boot
- B.UDP supports priority queuing to ensure DNS queries are answered first; the IPv4 identification field holds the sender's autonomous system number. A socket pairs a MAC address with a VLAN ID to identify one conversation
- C.UDP is connectionless and low-overhead - a DNS query and response are typically a single small exchange that does not require the reliability overhead of TCP's three-way handshake
- D.UDP automatically encrypts DNS queries to prevent snooping
Why C is correct
DNS queries are typically small (< 512 bytes) and require a single request-response. Using TCP would require a three-way handshake, doubling the round-trip time before the answer is received. UDP's connectionless nature allows the DNS client to send a query and receive an answer in a single round trip. If the answer is lost, the DNS resolver simply retries. The tradeoff (no guaranteed delivery) is acceptable because DNS retries are fast and cheap.
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