Auto Last Hop is a feature in F5 BIG-IP that makes sure return traffic goes back to the same device that originally sent the request, even if the routing table doesn't have a clear path to the client.

Simple Explanation:

Normally, the BIG-IP looks at the routing table to decide where to send traffic.

With Auto Last Hop, the BIG-IP remembers the source (MAC address) of the original request and sends the response directly back to it, ignoring the routing table.

This is especially helpful when:

The BIG-IP doesn’t have a default route configured.

The client is on a remote network, and routing is unclear.



Example:

If a client from a remote network sends a request, but the BIG-IP doesn't know how to route back to that network, Auto Last Hop ensures the response still reaches the client by sending it back the same way it came in.

Reference: https://my.f5.com/manage/s/article/K13876