What is the recommended default TTL of an IPv4 packet?

The recommended default Time to Live (TTL) value for an IPv4 packet is 64. TTL is a field in the IPv4 header that helps limit the lifespan of a packet across networks. Each time a packet traverses a router, the TTL is decremented by one, ensuring that packets do not circulate indefinitely due to routing loops.

When a packet's TTL reaches zero, it is discarded by the router and not forwarded further. The choice of a default TTL value is significant because it balances the need to allow packets enough hops to reach their destination while still acting as a safeguard against potential looping scenarios.

Historically, many operating systems and devices adopt 64 as a default TTL because it provides a good compromise, allowing most packets to reach their destinations while preventing excessive resource consumption from undeliverable packets. This value is recognized widely across different platforms and networking standards, making it a practical choice for default configuration.