What is DNS TTL and How Does it Affect DNS Propagation?

DNS TTL (Time To Live) is a special value present in all DNS records. It is an important value in the context of DNS because it has far-reaching implications for DNS propagation.

In this post, we will understand more about what TTL is, its role in DNS records, and how it affects the process of DNS propagation.

What is TTL?

TTL stands for Time to Live. It is a term commonly used when configuring DNS records and other forms of networking/computing, including databases, caching, etc.

In the context of DNS records:

“The TTL indicates the amount of time for which a particular DNS record has to be retained in the cache before being refreshed. For example, if there is a record called “X,” which has a TTL of 100 seconds, it means the record will be refreshed in the DNS cache every 100 seconds. (The DNS cache is where DNS records are temporarily stored so that they can be fetched quickly.)”

There are upsides and downsides to having both a short TTL and a long TTL. You have to decide the duration depending on the domain you’re managing, the level of performance you need, etc. 

To learn more about the pros and cons of a long and short TTL, navigate to the heading “Should the TTL be Long or Short?”. 

How does TTL affect DNS propagation?

TTL has a direct bearing on DNS propagation. DNS propagation is the process through/during which changes made to the DNS records are applied globally to all the different DNS servers. (The DNS propagation status of a domain can usually be checked using an online DNS propagation checker.)

The TTL of the DNS records decides how long they (the records) stay cached. If the TTL is short, the changes made to the records will be applied globally much faster. That is because the recursive resolvers and the local DNS caches will look for updates after a shorter amount of time.

Hence, we can describe the relation between the TTL and DNS propagation as follows:

Longer TTL = Slower DNS propagation

Shorter TTL = Quicker DNS propagation

Considering this straightforward relationship, having a shorter TTL may appear to be better and more advantageous. While it is true that shorter TTL leads to quicker DNS propagation, there are some downsides to it as well. But more on that later. Let’s first discuss…

What other factors affect DNS propagation?

Apart from the TTL (which is declared in the DNS records), some other factors affect DNS propagation as well.

For example,

• The local cache found on devices and browsers, etc., can sometimes retain the old DNS records even past their declared TTL. This can affect how long the changes are propagated to specific devices.
• If you make changes to the DNS settings, such as the nameservers, the TTL is set by the DNS registrar to a default value. This default value is around 24 to 48 hours. For these types of changes, you cannot set a custom TTL.
• CDNs are also a factor that can affect the DNS propagation time. If you are accessing a website through a CDN, the data stored in the CDN can take some time to be replaced.

Should the TTL be short or long?

Above, we’ve briefly discussed how there are pros and cons to both longer and shorter TTL. Now, let’s take a detailed look at both of them.

It is important to note that the pros of longer TTL are the cons of shorter TTL, and vice versa. In other words, the things for which longer times to live can prove to be beneficial are the same things for which shorter times to live can prove to be harmful.

How to find the TTL for your DNS records

Now, let’s talk about how you can find the TTL for all of your different DNS records.

There are two main ways in which you can do this. You can either go to your website’s hosting provider or use an online third-party tool. Visiting your website’s hosting provider can often involve a long signing-in process. Also, that can work only for websites or domains that you own yourself.

On the other hand, using a third-party online tool is quicker, and it can be used to find the TTL of any domain or website on the internet and not just your own.

Here are the steps that you can follow to find the TTL of your DNS records using an online third-party tool. (We’re going to guide you about the process using our own DNS lookup tool.)

• First of all, navigate to the DNS lookup tool by clicking on this URL: https://whatsmydns.me/dns-lookup

• Next, enter the domain name into the provided space

• Select the DNS server by clicking on the drop-down menu

• Click on the button that says “DNS Lookup”

• This will show you the results for all the DNS records for your domain. If you want to look for a specific record, you can select it before starting the process

That is it.

When the details about the DNS records are provided, you will be able to see the value of the record itself along with the TTL.

Common TTL Values for Various Records

Here are some recommended TTL values for common DNS records.

Here’s the updated table with TTL VALUE and IN HOURS columns:

How to change the TTL for your DNS records

The exact steps required to change the TTL for your DNS records can differ based on the domain registrar and the default control panel that it uses. However, we’re going to list the general steps below:

• First of all, log in to your domain registrar account. For example, if you’re using Namecheap or GoDaddy, log in to your hosting account.
• Go to the domain whose records you want to edit and open the control panel. (If you’re using Namecheap, for instance, the button will read “Go to Cpanel.”)
• After that, find the DNS records settings. (To continue the example of Cpanel, these settings can be found by clicking on the “Zone Editor” option.)
• Find the DNS record that you want to change and click on Edit.
• Reenter the TTL however you like by specifying it in seconds. 

Ways to speed up your DNS propagation?

One of the main ways to speed up DNS propagation is to set a shorter TTL. However, there are some other things that you can do as well, such as:

• Flush local DNS cache regularly: DNS propagation can be delayed due to data being stored in the local cache. If you flush the local cache regularly, you can speed up the propagation process. You can use the command ipconfig /flushdns in the command prompt to flush the local cache. 
• Use a fast DNS service provider: Using a fast DNS server provider can also affect the speed at which changes are propagated. You should use a DNS server that is known for its speed, such as Cloudflare.
• Make changes sporadically: Making changes to the DNS sporadically instead of collectively can also make a difference in propagation speed. If you make a lot of changes, all of them can take some time to implement.

Conclusion

The TTL of a DNS record is used to indicate the time for which the data is kept in the local cache before the resolvers ask for updates from the authoritative servers. Having a longer TTL can be beneficial for redundancy; in other words, it can lead to the cache providing data to the users even if something goes wrong with the data in the authoritative servers.

On the other hand, having a short TTL can be beneficial as the caches can be regularly updated with newer information.

If your website is a static website, such as a blog or a portfolio that does not undergo regular changes, keeping a longer TTL can be a smart idea. On the other hand, if your website relies on quick updates, such as a news website or an e-commerce store, then it is better to have a shorter TTL.

Thus concludes our article. Before you move on to the next one, be sure to check out the FAQs that we’ve provided below. You may find answers to your TTL-related questions below. 

FAQs

What is the lowest TTL that I can set for a DNS record?

The lowest possible time to live that you can set for a DNS record is 1 second. You cannot enter 0 in the field because then it won’t be considered.

However, while the lowest possible TTL is 1 second, some DNS service providers may have a minimal limit, such as 30 seconds or 60 seconds, because propagations after every 1 second are not usually feasible.

Should different DNS records have different TTL values?

Yes, different DNS records should have different times to live. It depends on how often the DNS record has to change.

For example, the A record or the AAAA record for a domain contains the IPv4/IPv6 addresses and hence doesn’t have to be propagated again and again. For these records, it’s fine to set a longer TTL.

On the other hand, the MX records contain not only the names of the mail servers but also the priority levels of each server. This information can change on a regular basis, which is why MX records should have a shorter TTL.

What happens if nothing is entered into the TTL field?

If nothing is entered into the TTL field, then the resolvers will take into consideration the TTL defined by default by the DNS server. This is usually around 24 to 48 hours.