Which protocols are used for domain name system (DNS) requests?

Both TCP and UDP are used for DNS requests based on the specific requirements of the query being made. Typically, DNS queries operate over UDP because it is a connectionless protocol that allows for faster transmission of small amounts of data, which is suitable for the common use case of resolving domain names to IP addresses.

However, DNS can also utilize TCP for certain scenarios, particularly when the response data size exceeds 512 bytes, as UDP has a limit on packet size. DNS requests for zone transfers between servers also rely on TCP, as this process involves larger volumes of data that benefit from the reliability and error-checking capabilities that TCP provides.

Thus, the use of both protocols reflects the flexibility in DNS operation to accommodate different situations, ensuring efficient and reliable communication in name resolution tasks.