What is TTL and how to use it?

Time is a key business asset that shouldn’t be neglected. Efficiency managing time directly reflects on productivity and money you can make. That works in all fields, computing and networking included!

What is TTL?

TTL or time to live is a mechanism for limiting the data lifetime or the number of times they can hop in a network or a computer. When the time set up for data to be alive expires, meaning it points zero seconds remained, those data will be discarded by machines (computers, routers, etc.). 

Why is TTL important?

TTL is a really important mechanism to control the existent data packets and traffic on a network. Networks are more and larger every day. The amount of data packets traveling across them is huge. Without a way to control them (expiry date), millions of old packets that complied their purpose many years ago could be still around, traveling but without sense anymore.

Time to live is a vital tool for detecting if data are still valid in contexts like networking, as we explained, and the cache memory of devices. Data detected as no longer valid can be discarded. 

TTL also permits you to get information about packets, such as the time they have been traveling around and the complete route they have followed. This information is very important in terms of security!

Besides, TTL totally influences another critical process, DNS propagation. Every time DNS records are updated or modified by you or your administrator, DNS propagation is required for the changes to get the full effect across all network servers. In other words, DNS propagation is the time that it takes for DNS modifications to be updated and available in the complete network. Yes, modifications are not available instantaneously in all servers because recursive servers save DNS data in their cache, the specific period the time to live establishes. Only when the TTL expires, recursive servers could refresh the data. Time to live can be an ally or an obstacle for DNS propagation.

How to use TTL?

You can make DNS propagation faster by setting lower TTL values. Let’s think that you change a DNS record, and the TTL is set to 3600 seconds. This means that in just an hour, the recursive servers could be able to look for the update that includes the change you made. If the set time to live value is higher, then the time you have to wait for the propagation to be completed will be longer.

Consider that DNS records comply with different functions, and not all of them necessarily have to be changed frequently. Identify the ones that constantly change and set a lower time to live. Then, you will have to wait less time for changes to be propagated and available in the whole network.

And for the ones that almost don’t change, establish a higher TTL. Once you know when they are going to require a change, be prepared! Reduce the TTL for their modifications to propagate faster. When they get updated in the whole network, you can change the TTL to a higher one.

Remember, with a lower TTL, DNS records will be stored less time on the recursive servers’ cache. With a higher TTL, they will remain longer there before getting the last update. 

So, like this, you can use the TTL to manage the DNS propagation time. 


Knowing what TTL is and how to use it is vital to administrate and optimise your online business. Never define the time to live value randomly! This task must be strategically thought not to affect the different processes.

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