DNS Cache: Definition and Working

A DNS cache is a temporary storage of DNS records that helps in speeding up the process of domain name resolution. When a DNS request is made to resolve a domain name to an IP address, the DNS server stores the resolved IP address in its cache for future reference.

When a subsequent request is made for the same domain name, the DNS server first checks its cache to see if the IP address is already stored. If it is found in the cache, the DNS server can quickly retrieve the IP address from the cache without having to go through the entire resolution process again, thus improving the response time.

However, DNS caches have a limited lifespan and the stored information can become outdated. To ensure accuracy, DNS servers periodically update their cache by purging old records and fetching new records from authoritative DNS servers.

In summary, a DNS cache works by storing resolved DNS records temporarily, helping to improve response times for repeated domain name resolution requests and periodically updating its content to ensure accuracy.