A DNS cache is a small memory storage that keeps track of recently visited domain names and their IP addresses, so your device doesn’t have to look them up again every time.

When you type something like “google.com,” your computer needs to find its IP address using the Domain Name System (DNS). Then, it gets stored for the next time. So when you want to visit that site again, your device checks if it already knows this IP address and if it does, it uses the cached results instantly. If it doesn’t, it asks the DNS server.

Think of a DNS cache as a list of phone numbers saved in your contacts: the first time you need the number you have to look it up but every time after, it’s saved. 

Cached entries don’t last forever. Each record has a TTL (Time To Live). After that time, it expires and is refreshed. DNS caching is important because it helps websites load faster (as there are no repeated lookups). It also means less traffic to DNS servers, which is more efficient.