DNS

What is DNS propagation?

When changes to DNS records occur, whether it’s due to a new
DNS configuration or a change in service provider, IP address or
hostname, the updated DNS records must propagate so the new
information will become visible to users.

What does DNS propagation mean?

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.

DNS propagation time

There’s no set amount of time for propagation, but DNS typically propagates within a few hours. On occasion, it can take up to 72 hours. 

Several factors determine the timeframe for propagation, including your internet service provider (ISP), your domain’s registry and the Time to Live (TTL) values of your DNS records.

How do internet service providers (ISP) affect DNS propagation times?

When you enter a URL into your address bar, a request is first passed to a local DNS recursive resolver (also known as a recursor or resolver), which is typically assigned by an ISP. The request then passes to several different servers before reaching an authoritative nameserver that holds the final answer for the original request. When ISPs ignore TTL values and keep records in cache after the records have expired, propagation can slow significantly.

How does Domain Name Registry affect DNS propagation speeds?

When you make changes to your domain’s authoritative nameserver, the changes must also take effect in the Top Level Domain (TLD) and root servers. When switching providers, waiting 72 hours before deleting records from the previous provider or discontinuing service can help mitigate delays.

How does TTL affect global DNS propagation?

Whether or not an ISP ignores TTL in DNS records, TTL values still affect propagation. The higher your TTL is set, the longer propagation will take. For example, when you make a change to a DNS record with a TTL of 86,400 seconds (24 hours), all servers will continue serving end users the old information until the end of this 24-hour period. Once the TTL has expired, servers will make a new DNS request to retriever any new information.

Lower TTLs (between 30 and 300 seconds) are better for those with domains that make regular updates to DNS records. In these cases, a high TTL is a disadvantage, especially when an ISP ignores TTL values. For mission-critical and life-or-death services, it’s advisable to set TTL to 30 seconds, the lowest value recognized by many resolvers. If you’d like to set TTL for lower than 30 seconds, make a test record first to ensure the resolver recognizes it.

Global DNS propagation checker

Online DNS propagation checkers can check to ensure your DNS record changes have propagated globally; we recommend running a check on multiple checkers for the most accurate results.

Here are a few propagation checkers:

How DNS propagates on the DigiCert® DNS Made Easy network

At DigiCert, any changes made to your DNS records are propagated instantly across all authoritative nameservers in our global network. This allows you to configure lower TTL values, which helps speed up propagation time. However, until TTL expires on the updated DNS record, recursors will still operate with the information they have in cache.