DNSvälimuistipalvelimet

DNSvälimuistipalvelimet, or DNS caching servers, are an essential component of the Domain Name System. Their primary function is to store recent DNS query responses to speed up future lookups. When a user's device requests the IP address for a domain name, like example.com, the request first goes to a DNS resolver. If this resolver is a caching server, it checks its local memory for a stored record of example.com's IP address. If the record is found and has not expired (based on its Time To Live or TTL value), the caching server immediately returns the IP address to the user's device. This significantly reduces the time it takes to resolve the domain name, as it bypasses the need to query authoritative DNS servers further up the hierarchy.

If the requested DNS record is not present in the cache or has expired, the caching server will then perform a recursive query. It contacts other DNS servers, starting with root servers, then TLD servers, and finally the authoritative name servers for the specific domain, to obtain the IP address. Once the IP address is retrieved, the caching server stores it in its cache for a duration specified by the TTL before returning it to the user. This process of caching not only benefits the end-user by providing faster internet access but also reduces the load on the global DNS infrastructure by decreasing the number of queries that need to be forwarded to authoritative servers. Organizations often deploy their own DNS caching servers for internal networks to further optimize performance and control.