The main purpose of TTL in networking is to:

The main purpose of Time to Live (TTL) in networking is to limit the number of routing hops that a packet can take within a network. Each time a packet is forwarded by a router, its TTL value is decreased by one. When the TTL reaches zero, the packet is discarded and not forwarded any further. This mechanism helps prevent packets from circulating indefinitely in the network due to routing errors or loops, thus managing network traffic and resources efficiently. By enforcing a limit on how long a packet can exist in the network, TTL plays a critical role in maintaining network stability and performance.

The other choices refer to different aspects of networking; for example, ensuring delivery of packets is more a function of the transport layer protocols like TCP. Establishing connection parameters pertains to how connections are set up, often handled by the transport layer as well. Enhancing packet security involves encryption and authentication processes rather than TTL, which is purely a routing efficiency mechanism.