What is Name Resolution?
Name resolution refers to the process of converting the human-readable names given to computers (such as hostnames and domain names) into the addresses required for communication between computers. On the internet, this function is handled by a system called DNS (Domain Name System). In DNS, translating a domain name to an IP address is called forward resolution, while translating an IP address to a domain name is referred to as reverse resolution.
DNS is comprised of numerous DNS servers distributed globally. No single DNS server retains all domain information; instead, it uses a system called delegation, which divides management responsibilities for each domain to separate servers, enabling distributed management of the information required for name resolution. Domains under management are called zones, and the DNS servers managing specific zones are known as DNS content servers or authoritative DNS servers. On the other side, DNS cache servers receive user requests, query other DNS servers, and relay the results to the users. Clients that initiate name resolution requests to DNS servers are called resolvers.
The name resolution process in DNS begins with a resolver querying a DNS cache server. The cache server then contacts a root server, which manages the root domain at the top of the domain hierarchy. The request is passed down sequentially to DNS content servers managing lower-level domains until it reaches the authoritative DNS server for the target domain. This server provides the mapping of the domain name to its corresponding IP address, which is then returned to the resolver. The DNS cache server stores the obtained information in its cache for a certain period. If the same query is made during this timeframe, the cached content is returned to the resolver, reducing the need for repeated queries.