TTL explained for beginners

When it comes to life and businesses, time is essential. Dates, duration, and deadlines are tools to organize, measure, and adjust processes to make them efficient.

Computing and networking are no exception. Their processes are strongly ruled by time.

TTL explained

TTL means time-to-live. It sounds like a cool title for an action movie, but it’s not. TTL is a value that establishes the number of hops of a data packet travel on a network, or time data can live in the cache memory of a machine (like in DNS records).

When this defined number of hops or time comes to its end, the packet or the data are no longer valid. Therefore they will be discarded by routers and other machines.

Through TTL, network administrators can define the time for data to be alive based on the objective they accomplish. Once they complete their tasks, they get discarded.

Why does TTL matter?

TTL helps to control data packets’ traffic

Daily, the Internet involves constant communication. There’s a permanent exchange of data packets between networks, applications, and machines. This is the way it has worked since its birth in the 1980s. Without a way of limiting the existence of data packets, cyberspace could be saturated. Old and without purpose, data packets could still be traveling around. That’s why TTL matters! It’s a helpful mechanism for controlling traffic.

Administrators define a TTL for data packets. Machines read this value so they can discard or accept them. A simple but efficient mechanism to keep the order of the massive traffic on the Internet realm.

TTL reveals more information about data packets

TTL allows you to know the complete route and the time data packets have been around within a specific network.

Every data packet is sent by a source, with a specific purpose, to a destination. During its trip, the packet will touch different hops on the network. Routers will read its TTL to know if it’s still valid. If it has not expired yet, it will go forward. If it’s expired, it will be discarded.

Routers will report the expiration of a data packet to its source through the Internet Control Message Protocol (ICMP). And here comes an interesting fact. An ICMP message will take a certain time to arrive at its destination. Knowing that time, you can track the hops the data packet touched when its TTL was not expired. So you can figure out its route.

TTL helps to make DNS propagation quicker

TTL also works for DNS. In this case, it points out the time a DNS record is valid. You should set up a lower TTL value if you need to edit a DNS record constantly, so it propagates quickly. Conversely, you can set up a higher value and lower the DNS servers’ usage.


TTL is key for the operation of online businesses. It’s a small value that can greatly impact your processes. Take it as seriously as it is!