What is DNS?
The Domain Name System (DNS) makes life easier for humans. One of the main reasons to use DNS is because humans have an easier time remember names than they do numbers. DNS maps an IP address to a host name. This means that instead of having to memorize IP addresses, we simple have to remember the URL for a website. For example, to access this website, instead of having to remember 220.127.116.11 I just have to remember adminhacks.com.
All computer functions are based on binary math. Computers use numbers to work and communicate with each other. Humans use words to communicate. DNS translates the words into the numbers.
DNS is served by DNS servers. To be able to use domain names such as adminhacks.com, your computer must be able to communicate with a DNS server. The DNS server translates the domain name into an IP address.
Diagnosing DNS can be easy. If you ever come into a situation when a domain name does not work but an IP address does work, then DNS is the problem. Check your DNS settings and make sure that your DNS server is functioning properly. In many home networks, the router also serves as a DNS server.
There are other functions that DNS plays. DNS allows the mapping of multiple IPs to a single domain name. This allows many different computers to reply to a single query. This is called anycast. Lets say adminhacks.com has three different webservers hosting the website. One in North America, one is Europe and one in Asia. Using DNS anycast, the webserver nearest you will be the one to reply when you type adminhacks.com into your browser. This is possible because of DNS.