address information of a domain<\/a>.<\/p>\n\n\n\nDetailed explanation<\/h4>\n\n\n\n
The Domain Name System (DNS) communication occurs through a series of steps. For example, that involves various entities, including the client, DNS resolver and root name servers.<\/p>\n\n\n\n
Here\u2019s a step-by-step overview of the DNS communication process:<\/p>\n\n\n\n
Client Initiates DNS Query.<\/strong> The process begins when a client, such as a web browser, initiates a DNS query. It requests the IP address corresponding to a domain name.<\/p>\n\n\n\nFor example, the client wants to resolve the domain name \u201cexample.com\u201d to an IP address. DNS works the same way, either for ipv6 or ipv4 addresses.<\/p>\n\n\n\n
DNS Resolver Receives the Query.<\/strong> The DNS resolver, usually provided by the client\u2019s ISP or network, receives the DNS query from the client. The resolver checks its local cache to see if it has the IP address for the requested domain name. There is a DNS hierarchy.<\/p>\n\n\n\nIf the information has expired, or else if it’s not present in the cache, the DNS server resolves the query.<\/p>\n\n\n\n
Recursive Query<\/strong>. The DNS resolver performs a recursive resolver query to find the IP address for the domain name.<\/p>\n\n\n\nIt starts by querying the root DNS servers. Then sends a request for the tol level domain TLD servers that handle the requested domain extension (.com, .net, etc.).<\/p>\n\n\n\n
Then\u2026<\/h4>\n\n\n\n
TLD Name Server Resolution.<\/strong> The root DNS servers respond to the resolver with the IP address of the appropriate TLD name server.<\/p>\n\n\n\nThe one responsible for the requested domain extension (e.g., the .com TLD server). The resolver then queries the TLD name server.<\/p>\n\n\n\n
Authoritative Name Server Resolution.<\/strong> The TLD name server responds to the resolver with the IP address of the authoritative name server. The one responsible for the specific domain (e.g., the authoritative name server for \u201cexample.com\u201d). The resolver then queries the authoritative name server.<\/p>\n\n\n\nResponse and Caching.<\/strong> The authoritative name server responds to the resolver with the requested IP address. The resolver caches this response and sends it back to the client. The client can now use the obtained IP address to establish a connection with the desired resource (e.g., a web server).<\/p>\n\n\n\nThroughout the process, the devices use UCP or TCP packets to exchange DNS messages. It depends on the specific query and response sizes.<\/p>\n\n\n\n
The DNS communication is efficient and distributed. For example, allowing for the resolution of millions of domain names across the internet.<\/p>\n\n\n\n
It\u2019s worth noting that subsequent DNS queries for the same domain can benefit from caching at the resolver level. As a result, that avoids the need to repeat the entire resolution process unless the cached data has expired.<\/p>\n\n\n\n