What is DNS propagation?

Whether it’s for a new DNS configuration, you’re switching service providers, or you need to change an IP address or hostname, there are times when DNS records require updates. When record changes occur, they need to propagate new information to be visible to users. This resource will cover the ins and outs of DNS propagation so you can plan your record changes accordingly.

What is DNS propagation?

DNS propagation is the time it takes updates to DNS records to be in full effect across all servers on the internet. Changes don’t take effect instantaneously because nameservers store domain record information in their cache for a certain amount of time before refreshing. Your domain won’t experience downtime from properly planned record changes, but some users will still see a cached version of your site until all servers have propagated.

How does it work?

Those changes are first made on your authoritative DNS server when you change your DNS records. The authoritative DNS server for your domain is the one that contains the official records for your domain. Once the changes are made on the authoritative server, the updated records are propagated to other DNS servers on the internet.

During propagation, DNS servers worldwide update their cached records with the new information. Depending on various factors, DNS propagation can take anywhere from a few minutes to 48 hours.

Factors that affect DNS propagation time

• TTL or Time to Live: TTL refers to the time DNS information is allowed to exist (live) on a local or remote DNS server. For instance, if your DNS record has a TTL of 24 hours, all servers will continue to display the old information to end users for 24 hours, after which the servers will create a new DNS request to get the latest information.
• ISP or Internet service provider: ISPs cache DNS records so that your site loads faster to end users worldwide. Some ISPs ignore TTL values and keep DNS records in the cache even after the TTL has expired, which can cause DNS propagation to take longer to complete.
• Domain name registry: When you change your domain’s authoritative name server, the changes affect the top-level domain (TLD) and root servers. Depending on their TTL, the DNS propagation can be prolonged further.

How to speed up DNS Propagation

If you want to help speed up the DNS propagation process, you can:

• Lower TTL (Time-to-Live) Value – If you know you’ll be making changes, set your TTL to a lower value a day or two before implementing them. This will prompt servers to refresh the DNS information more frequently.
• Use a CDN – A Content Delivery Network (CDN) can cache and serve content globally, which may help mitigate some propagation delays.
• Purge caches – If you control any DNS servers yourself, you can manually clear their cache to force them to update sooner.
• Flush Public DNS Databases – Some public databases will allow you to flush the DNS cache quite easily. You can do this in Google Developers by visiting the Google Public DNS console. You can also flush the cache on OpenDNS with their CacheCheck tool.

How to know if DNS propagation is complete

There is no perfect way to monitor your global DNS propagation because it would be incredibly difficult to monitor the countless number of DNS servers located around the world. However, tools such as DNS propagation checkers can provide insight into propagation times. These solutions work by checking new domain DNS records on a sample of global DNS servers to see if propagation occurred. While not perfect, these insights can help organizations plan for DNS changes and reduce downtime.

To avoid such estimations, organizations can use an authoritative DNS provider that helps ensure DNS changes are quickly propagated worldwide.

Conclusion

Understanding DNS propagation is essential for anyone who owns a website or manages a domain. It’s essential to be aware of the duration necessary for modifications made to your DNS entries to become effective, as well as how you can verify if the changes have propagated correctly. We’ve covered why DNS propagation takes time, tools you can use to check propagation status, and tips on speeding up the process.

If you’re experiencing issues with DNS records not propagating or affecting email delivery, understanding the root cause will help you troubleshoot effectively. Remember that patience is key when waiting for DNS changes to propagate fully across all servers.