TTL: Definition
Time-to-live (TTL) is the value that specifies the time period or number of hops that a data packet must travel to be alive. Either across the network or in the memory cache. It will be terminated when this timer expires, or the data packet reaches its hop limit. Data packets are not all the same; they vary in size and shape, but each has a different TTL. The amount of time data packets should live in a device to perform their missions should be determined.
The way TTL works
If routers are not regulated, massive amounts of traffic will be routed around them indefinitely. Each data packet must be assigned a limit or expiration date to get around this. This allows you to track their progress and determine how long they’ve been present. Furthermore, packets traverse network nodes to reach their destination. As a result, every data packet includes a TTL value. If time or hops are available, routers receive the packet and forward it to the next network point. However, if the TTL indicates that no more hops/time is available, routers will stop transferring it.
How to check it?
- Windows
If you are a Windows user, you can use the Nslookup command. You can check a specific DNS record, such as SOA, A, AAAA, MX, and others. Simply replace the DNS record type in our example below with the one you want to check.
So, find and open the Command Prompt and enter the following:
–types=a example.com nslookup
- macOS or Linux
For Linux or macOS users, there are more possibilities. For example, you can use the Terminal to select which commands to run.
One of them is the Dig command, which may display the TTL value of various DNS records and provide information about them. For example, to access the A record, type the following.
dig a example.com
Another alternative is to use the Host command, which works similarly:
host –a example.com
This command will display all of the accessible DNS records and their TTL values.
Why do we need TTL?
To control the number of data packets that exist, we need TTL. Have you ever considered how many data packets are sent across a network every minute? Consider a situation in which there is no expiration date. Even the first data packet ever sent could be moving nonstop without a purpose.
Time-to-live aids in optimizing data packet traffic, indicating whether the data they contain is still valid, and allows for the retrieval of information about them. For example, you can find out how long a data packet has been around and track its path. In a cyber world full of risks, this information is extremely useful.
Conclusion
Let’s review. TTL (Time to Live) is a method that determines how long data in a computer or network can live. It will indicate whether the information is current or needs to be updated soon. So, it facilitates data updating.