What Is DNS Propagation?

Date First Published: 10th May 2022

Topic: Computer Networking

Subtopic: Internet Protocols

Article Type: Computer Terms & Definitions

Difficulty Level: 8/10

Learn more about what DNS propagation is in this article.

DNS propagation refers to the period of time that it takes for changes to DNS records to take effect across the entire web. This can take between 24-72 hours. For example, when updating the nameservers of a domain name, it will immediately start pointing to the server specified. However, in order for these changes to fully take effect for all internet users, the cache needs to fully expire.

Note:

The cached DNS information is stored by ISPs and after a period of 24-72 hours, this cache expires. ISPs cache DNS information as it speeds up the loading time and reduces the number of full DNS lookups required. Different ISPs have different cache refreshing intervals.

DNS information can also be cached locally on a computer. This works in the same way as ISPs cache information. However, it is only stored on a local computer. In order to make sure that the computer does not have outdated DNS information, DNS cache can be flushed and the cache of the web browser can be cleared.

How To Speed Up DNS Propagation?

DNS propagation can be sped up in three ways:

1. Using the hosts file on the local computer.

   This is the quickest method of speeding up DNS propagation, since the domain name will immediately point to the specified IP address. However, this change will only take effect on the local computer rather than the entire web. In order to point the domain name to the IP address, find the hosts file, which is located in ‘c:\Windows\System32\Drivers\etc\hosts’. This path can be copied into File Explorer.

   Once you have found the file named ‘hosts’, edit it, and then add an entry. The entry should be:

   (specified IP address) (domain name)

   For example, if the domain name ‘example.com’ was pointed to the IP address ‘127.0.0.1’, the entry would be:

   127.0.0.1 example.com

2. Within 24 hours before changing the DNS record, set the TTL (Time to live) down to 300 seconds. This will help reduce the chances of devices caching the DNS records for extended periods of time. This change will need to be made before updating the DNS record.
3. If the nameservers have already been changed, request popular DNS providers to flush their DNS records for the domain name. This can be performed in three DNS providers, called Google DNS, Cloudflare, and OpenDNS.

After performing this step, this will speed up the period of time that changes to the DNS information of a domain name take.

How To Check If DNS Propagation Has Completed?

DNS propagation can be checked by a DNS checker, called Dnschecker.org. This DNS checker performs a quick DNS propagation lookup for a domain name from all available DNS servers and locations to check whether the DNS records are fully propagated around the world and if the DNS lookups resolve.

DNS propagation depends on four factors:

• The ISP.
• The device (whether it has cached the DNS information).
• The geographical location.
• The TTL.