What is the default TTL (time to live) on a router for an IP packet?

The default TTL (Time to Live) value for an IP packet on a router is typically set to 64. This value serves an essential function in IP networking by preventing packets from circulating indefinitely in case of routing loops. Each time the packet passes through a router, the TTL value is decremented by one. When the TTL reaches zero, the packet is discarded, thus stopping the possibility of infinite loops.

In most operational environments, using a TTL of 64 offers a good balance, providing sufficient hops for packets to traverse through a network while minimizing the risk of network congestion due to undeliverable packets. Many operating systems and networking devices adopt this default value, aligning with industry standards.

This understanding of the TTL value is crucial for troubleshooting and analyzing routing behavior in networks, helping network engineers and administrators maintain efficient communication paths.