DNS & Web Hosting
Computer Science: OCR GCSE, topic 1.3.13
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 discovers that it 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.
Web Hosting
Web hosting is the act of keeping a website on a server, and allowing clients to request to see the pages of the website.
Websites
- A website is a collection of webpages which are linked together using hyperlinks.
- A user can click on hyperlinks to navigate the website.
Hosting a website
- A web server is a dedicated computer on the Internet which responds to HyperText Transfer Protocol (HTTP) requests by returning webpages.
Setting up a web server
- Some people choose to host their own website, but this can be difficult for many reasons:
- There are a lot of security risks.
- It can be difficult to make sure that the server does not go down, for example if there is a power cut.
- Web servers are expensive.
Hosting providers
- Most people opt to use a web hosting company. A web hosting company will charge a monthly fee in return for hosting your site for you.
- Web hosting companies will:
- Host your website.
- Regularly back up your site.
- Apply security patches for you.
Test yourself on DNS & Web Hosting
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?