When a domain name is typed into a browser, it is the DNS (Domain Name System) that translates this domain name into an IP address in order to locate the website. The sole responsibility of a DNS server is to take domain names and associate them to an IP address.
When a website is moved to a new server (with a different IP address), or a new domain is registered, there is a change of IP address. Every DNS server in the world needs to update its record of what IP is associated with this domain. This is called propagation. In other words, propagation is the time it takes for the DNS (Domain Name System) to update globally following a change to DNS.
Changes to DNS records do not propagate throughout the Internet immediately, as all server caches first need to expire and refresh. The amount of time this process will take depends on the update:
DNS changes: 2 – 24 hours
NS updates: 24 – 48 hours