DNS lookups that are less than 512 bytes are typically perfo

DNS lookups that are less than 512 bytes are typically performed on which of the following protocols and ports?

A. UDP 53

B. UDP 69

C. TCP 53

D. UDP 161

Solution

A. Although RFC 1035 does allow DNS lookups over TCP this service is provided for only when lookups are greater than 512 bytes, typically UDP 53 is used. Answers B, C, and D are incorrect because UDP 69 is used for TFTP, TCP 53 is used for zone transfers, and UDP 161 is used for SNMP