DNS servers primarily use the "Domain Name System" or "DNS" protocol to communicate with each other. The DNS protocol operates on UDP (User Datagram Protocol) or TCP (Transmission Control Protocol) at the transport layer of the internet protocol suite.
When DNS servers need to communicate with each other to resolve domain names or exchange DNS information, they typically use the DNS protocol over UDP for most DNS queries. UDP is a lightweight, connectionless protocol that offers fast communication but does not guarantee reliability or error correction.
However, in certain cases where the DNS response exceeds the maximum size limit of UDP packets (around 512 bytes), DNS servers may switch to TCP for DNS communication. TCP provides reliable and ordered transmission of data, making it suitable for larger DNS responses and other situations where reliability is crucial.
DNS servers communicate with each other using a combination of DNS query messages and DNS response messages. These messages contain various DNS record types, such as A records, CNAME records, NS records, and more, which allow DNS servers to resolve domain names and provide the necessary information for the resolution process.
Overall, the DNS protocol enables DNS servers to exchange information and work together to provide domain name resolution services, translating domain names into their corresponding IP addresses and facilitating communication across the internet.