Domain Name Service
Computer Science: OCR A Level, topic 3.3.8
Domain Name Service (DNS)
When a client sends a request to the server, it has to use an Internet Protocol (IP) address so that we can find the correct server. Modern web browsers allow us to enter a domain name instead, which the DNS translates.
Why use the DNS?
- Domain names are much easier to read and remember than IP addresses.
- Computers have to use IP addresses to communicate over the Internet Protocol.
- The DNS converts these domain names into IP addresses for us.
DNS lookup
- When we have a domain name, we send a request to the nearest DNS server asking for the IP address associated with that domain name.
- The DNS server responds with the correct IP address.
- The client can then use this IP address to send their original request.
DNS miss
- If a DNS server does not have an IP address associated with a particular domain name (a DNS miss), then it can ask other DNS servers that it knows about.
- By continuing to ask other, larger DNS servers, we will eventually resolve the IP address and send this to the original client.
Test yourself on Domain Name Service
Why do we use domain names instead of IP addresses?
What happens when we have a DNS lookup?
What is it called if a DNS server does not have an IP address associated with a particular domain name?
What happens when we have a DNS miss?