DNS
Domain Name Systemis the internet service that maps Internet domains into corresponding IP addresses.
DNS database is distributed and replicated among many DNS servers, so when you change your domain's IP address (i.e. change your hosting company ), the changes take a while to propagate.
The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address.
For example, the domain name www.example.com might translate to 198.105.232.4 .