DNSvälityksellä

DNSvälityksellä, often translated as DNS relay or DNS forwarding, refers to the process where a DNS resolver receives a DNS query and forwards it to another DNS server for resolution. Instead of directly querying authoritative name servers for the requested domain, the initial resolver acts as an intermediary. This is a common practice in many network infrastructures, particularly within organizations or by Internet Service Providers (ISPs).

The primary purpose of DNS relay is to centralize DNS lookups and introduce caching mechanisms. By having a central DNS relay server, multiple clients can share the same cache, reducing the need to repeatedly query external servers for frequently accessed domains. This can lead to faster response times for users and a reduction in the load on upstream DNS servers. Additionally, DNS relay can be used for implementing security policies, such as blocking access to certain domains or performing content filtering before forwarding requests. It also simplifies network management by allowing administrators to configure DNS settings in one place.

In practice, when a client makes a DNS request, it is typically sent to a local DNS server, which is configured to act as a DNS relay. This relay server checks its cache. If the information is present, it is returned to the client immediately. If not, the relay server forwards the query to one or more upstream DNS servers, such as an ISP's DNS servers or public DNS resolvers like Google DNS or Cloudflare DNS. Once the upstream server provides the answer, the relay server caches it and returns it to the client.