packet contains source and destination, not all router hops. At last the packet will arrive back to router1, which will check for matching packet ID and route it accordingly through router2 or router3 or directly to PC1 (which was connected in the same network segment as router1). The packet doesn't return If router1 routing table does not have any route to 192.168.1.0/24, and PC3 tries to access a resource outside its own network, then the outgoing routing will work until the reply is fed back to router1. Since the route is unknown to router1, it will go to router1's default gateway, and never reach router3. In the logs of the resource they will trace the request, but the requestor will never get any information. The packet will die because the TTL-value decreased to less than 1 when it was traveling through the routers, or the router will see that it has a private IP and discard it. This could be discovered by using the Microsoft Windows utility PathPing or MTR on Unix-like operating systems, since the ping will stop at the router which has no route or a wrong route. (Note that some routers will not reply to pinging). Utilities Various utility software can show the default gateway. On Windows, ipconfig may be used, while on Unix systems, ifconfig or netstat may be used. On Linux netstat has been superseded by iproute2. References External links The Linux Documentation Project Routing