DNS Search

What is DNS Propagation?

Changes to DNS do not always take effect immediately and globally. Typically a period of up to 24 - 48 hours is quoted when you make a DNS change.

Any time that DNS changes are made (on any level), you need to wait for propagation to complete.
During propagation, traffic may come to either the new DNS records or the old DNS records. One person may see the new server while someone else sees the old one. Also, yourdomain.com may work while www.yourdomain.com does not. All of this is normal during propagation.

What happens during DNS Propagation?

DNS stands for Domain Name Service. Every time you go to a web site using a domain name, you are using DNS. Your request for domain.com goes to your local primary or secondary DNS server (which is usually administered by your ISP), or could be held locally on your PC. Your local DNS server checks its records to see if it "knows" what IP address that domain points to. If it does, then it returns that result straight away without further checking. If it does not, then it sends a query to the Root DNS servers and gets the result from there.

Your local DNS server then caches (makes a copy of) this information. This caching (copying) process is essential: not only does it speed up future queries, it also reduces load on the Root servers. It is this copying (caching) process that leads to propagation.

Your local DNS server does not keep that information forever. Instead, it keeps the information for a certain amount of time, at which point it deletes it. The next time (after the information is deleted) that you try to visit that domain, the process starts all over again. The time the information is kept varies greatly but it typically 24-48 hours.