I have been wondering for a long time how the IP Packet will traverse from end host to a L2 switch to next hop and another routers and finally to another end of a host. What is the source & destination IP address,MAC address along the traversal of the packet?
Excellent explanation. The only thing i would add is when it gets to the default-gateway router.
Before the router resorts to it's default route (if indeed it has one) it will consult it's routing table to find the longest match on the destination host.
If it doesn't have an explicit entry for that subnet and assuming normal routing procedures and ip classless is turned on then it will use the default route.
Edit - oops one more thing.
Step 1 with the router. If the router forwards the packet onto another router then the source MAC is the exiting interface, the destination MAC is the interface on the next hop router that receives the packet.
The IP source and destination will always stay the same.