Time to Live (TTL) What is Time to Live (TTL) in Networking? Time to Live (TTL) is a value in data packets that specifies the maximum number of hops the packet can take before being discarded, preventing infinite loops in networks. Explanation Each time a packet passes through a router, its TTL value decreases by one. When TTL reaches zero, the packet is discarded, ensuring efficient data routing. Practical Example of TTL A DNS query uses a TTL value to limit how long cached data is considered valid, ensuring up-to-date responses.