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.