What is DNS TTL (Time To Live)?
Tags: dns, ttl, route53, aws
Published: 2021-12-29 17:41:55

## What is time-to-live (TTL)?
Time-to-live (TTL) is a value for the period of time that a packet, or data, should exist on a computer or network before being discarded.

The meaning of TTL, or packet lifetime, depends on the context. For example, TTL is a value in an Internet Protocol (IP) packet that tells a network router when the packet has been in the network too long and should be discarded.


`Here's the full video along with a hands-on demo that's based on TTL (time-to-live)👇👇`
[![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/xbnyuc6qtztnpqrisd56.png)](https://www.youtube.com/watch?v=QEmjX9OaGyU)
 

## How Does TTL Work?
TTL's basic function revolves around managing information packets in relation to DNS requests. When one of these packets is created and transmitted through the internet, there is a chance that it will pass, continuously, from router to router forever. To prevent this from happening, each packet has a specific TTL or hop limit. It is also possible to examine the TTL log of a data packet to obtain information on how it has moved through the internet over the course of its travels.

Within each packet, there is a specified place where the TTL value is stored. This is a numerical value, and it indicates how much longer the packet should move around the internet. When a router receives a data packet, it takes away one unit from the TTL count before sending it on to the next destination within the network. This continues to happen until the TTL count within the packet drops all the way down to zero.


## What is time-to-live in HTTP?
In Hypertext Transfer Protocol (HTTP), time-to-live describes the number of seconds it takes for cached web content to return before the webserver has to check again to ensure that the content is "fresh."

Settings on the webserver define a default value. Still, cache-control tags, which define the kinds of servers, if any, can cache the data, or expired tags, which represent a date and time when the content is stale, can override it in the HyperText Markup Language page headers.

## What Are TTL Values?
When you set TTL values for your website, you choose a value in seconds. For example, a TTL value of 600 is the equivalent of 600 seconds or ten minutes.

The minimum available TTL is usually 30, equivalent to 30 seconds. You could theoretically set a TTL as low as one second. However, most sites use a default TTL of 3600 (one hour). The maximum TTL that you can apply is 86,400 (24 hours).

Technically, you can set any TTL value between the minimum and maximum parameters. Later in this article, we’ll discuss how you can choose the best time to live value for your site.


## How Should You Choose a TTL?
Deciding on a suitable TTL for your needs can be challenging. Fortunately, there are some general guidelines that you can follow to see what fits your site best.
We recommend a TTL of 1-24 hours for most sites. Remember that TTL values are measured in seconds, so this is the equivalent of 3,600 to 86,400 seconds.

This TTL value can reduce loading time, which improves the user experience for your visitors and can decrease your bounce rate. The longer the better is a general rule, but remember to schedule any website maintenance accordingly.



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