The TTL field in an IP packet is used to limit the number of hops a packet can take before it is discarded, preventing routing loops and ensuring that data does not circulate indefinitely on the network. Each time the packet passes through a router, the TTL value is decremented by 1. When the TTL reaches zero, the packet is discarded by the router. Other options, while related to general network operations, do not accurately describe the primary function of the TTL field.