I replaced my aging fileserver with a new server running ESXi 5.1 and migrated my fileserver in a virtual machine running on it. Now I have the following problem with this VM:
- I'm getting the correct IP via DHCP (reservation via MAC address works)
- I cannot ping the gateway (10.0.0.1)
- I can ping the DHCP/DNS server (10.0.0.2)
- I can ping other machines on the network
- Pinging a host on the internet I can resolve it's IP address (due to the reachable DNS server), but cannot ping the resolved host
After changing the IP to a different, static IP I can ping the gateway as well as the internet.
I'm using a single subnet (10.0.0.0/24), the Routing table on the machine is correct.
The gateway is a Linksys E4200 router (with the original firmware).
I was using DHCP reservation es well before I moved the DHCP/DNS functionality from the router to a Raspberry Pi. I only changed the MAC adress on the reservation table of the Pi, not on the router, and the router was still referring to the MAC-address of the old server.
After removing the entry from the DHCP reservation table of the router the pings suddenly came back.
I guess the Linksys E4200 router uses the DHCP reservation table to resolve IPs to MAC adresses, resulting in the ping answers going to the wrong MAC address.
Might be a very special usecase, but maybe this spares someone else a headache.
To force an ARP cache update on your neighbours, you can simply run
arping -U x.x.x.x -c3