What is DNS Propagation, And Why is It A Lengthy Process?

DNS propagation refers to the process of updating and distributing any changes made in the DNS records of a domain across the internet. 

So, if you are a domain manager/webmaster and published a new record like a CNAME or MX record, the whole process of sending and storing those records in worldwide DNS servers is called DNS propagation.

This process takes a lot of time, usually anywhere from 24 to 72 hours. There are several reasons, most of which are out of your control. So, you cannot affect them in any way to reduce the propagation time. 

Let’s examine these reasons and understand why DNS propagation can take such a long time.

Reasons Why DNS Propagation Takes So Long

• DNS Caching and ISP Delays

DNS caching is a phenomenon where a DNS server will pull DNS records about a domain from its nameservers and store them in its cache. This way, when it is queried for that domain, it can provide the records itself rather than doing a lookup to find the nameserver.

ISPs across the world have their own DNS servers that cache a lot of records from different domains. However, a cache is not infinite storage. It needs to be cleared from time to time to make space for new records.

The frequency with which these caches are refreshed, affects DNS propagation. If a cache is cleared after every three days, it means new DNS records cannot be obtained for those three days (hence a 72-hour propagation time). 

There are different factors that affect how long a DNS cache retains old data. You can control some of these factors. Keep reading to find out all of them and understand which ones you can affect and how.

• DNS Record Time To Live (TTL)

So, one of the things that matters in DNS caches is the records TTL. The TTL is a figure in all DNS records that mandates how many seconds a DNS server has to wait before obtaining a new record copy. Each DNS record has a different TTL value based on best practices and guidelines. For example, NS records usually have very large TTLs, such as 86400 (24 hours). An A record, on the other hand, can have TTLs ranging from 180 (3 minutes) to 3600 (1 hour).

So, if the version of a record stored in a cache has a high TTL, a new version of that record will not be solicited until the time specified by the TTL has passed. So, some records can take way longer to propagate than others. 

Typically, TTLs are not kept short because that results in too many queries to authoritative name servers, which can overload them. So, if you follow best practices, then you will have to wait at least 24 hours before your new records are propagated to completion.

You can use tools like whatsmydns.me to check the progress of your DNS propagation worldwide.

• Registrar Side Delays

Domain registrars provide authoritative DNS servers for your domain. Any records you create are first published on these servers, and then they are propagated to the rest of the world.

Now, you can create your records on your domain manager dashboard, but it's up to the domain registrar to decide when to publish them. Any delays here result in more time added to your DNS propagation. You can’t do anything about this because you can’t control the domain registrar. 

Most registrars push the updates promptly, but plenty of others wait a day or two before doing so. This is why you should be careful when signing up with a registrar.

How To Hasten the DNS Propagation

Here are a few things you can do to improve your DNS propagation speed.

• Configure Lower TTLs

TTLs determine how long a server waits before refreshing the records it stores. If you configure your TTLs to be lower than usual, the server will replace them faster.

This way, you can reduce the time taken for DNS propagation by a few hours. However, it is not recommended that the TTLs be lowered beyond the confines specified in best practices. 

• Use a Global DNS Provider

A global DNS provider like Cloudflare or Google has DNS servers worldwide. If you use their authoritative servers for your domain, your records will propagate faster through their international network. 

Such providers also push updates promptly, so you don’t have to worry about unnecessary delays. 

• Use CDNs

Content delivery networks can help with propagation delays. DNS providers provide most CDN services, so if you can, use a service with Anycast DNS. With Anycast DNS, routing between DNS servers is vastly improved, which reduces latency and improves propagation times. CDNs also reduce the dependence on ISP caching because they have their own DNS servers. Users can bypass the ISP DNS servers and use the CDN DNS instead.

Once again, your best bet is to use Cloudflare, which has an extensive CDN network on top of its DNS network. 

Conclusion

So, there you have it, the answer to what DNS propagation is and why it takes so long. You also learned ways to reduce the time it takes to propagate new records.

However, keep in mind that it is impossible to remove propagation delays altogether. You can reduce it by a few hours. However, even that much is pretty good, so you should use what you can.