Can't ping ESXi 4 host by name or IP only from vCenter server, works from any other machine

[MrBigFeathas]

I am at a loss here. I have a 4 node ESXi 4 cluster. When I came in today all 4 nodes were not connected in vCenter. No problem. restart management agents and all will be fine. I restarted the management agents on all 4 hosts. 3 of them cam back in vcenter. 1 never did. The one that didn't I cannot ping by hostname or IP from the vcenter server. Also, I cannot ping the vcenter server IP from that ESXi host. All 4 nodes have the exact same netowrk config. I can ping the ESXi host and vCenter server from any other machine in my company that I've tried.

I am hoping I have an option besides rebooting the ESXi host but I probably don't. It's just weird that those two machines can't see eachother but every other machine can see both of them.

[MauroBonder]

Check if all hostnames are registred with FDQN on DNS.

Check if all ports are opened in firewall http://kb.vmware.com/kb/1012382

Please, don't forget the awarding points for "helpful" and/or "correct" answers. 

Mauro Bonder - Moderator

[MrBigFeathas]

They are, and I can't even ping by IP in either direction.

[awliste]

Check switch? Check ARP tables? Check DNS? Interfaces all up and working? nobody monkeyed with hosts file on vCenter? Everybody in right VLANs?

[MrBigFeathas]

Ok, so I restarted the vcenter server and it can now ping the ESXi host. No luck pinging vcenter from the ESXi host though. I really can't reboot the ESXi server. I've restarted the management network and agents about a million times. Do I have any other option?

[MauroBonder]

Did you have VLAN ID ? If yes, you aldreay configured this in port group ?

[MrBigFeathas]

There is no VLAN set on any of the hosts

[Prime201110141]

Hi MrBigFeathas,

1. Check wether all your ESXi hosts & vCenter in the same subnet with valid ip to that subnet.

2. If you have VLAN on your network, recheck the VLAN IDs and respective routing.

3. Check wether your vCenter's same IP had been assign by someother person to another system.

4. Check wether your vCenter's network is assign to the correct VMNetwrok (if you have many).

5. Check wether your vCenter is infected by a virus or malwear.

6. If ESXi hosts & vCenter's IP address assigned by DHCP server, double check.

7. Finally try Diagnose and repair on vCenter Server (you can do this as a 1st option as well )

                     Go to Control Panel -> Network and Internet -> Network and  Sharing Center-> Diagnose and repair. Alternatively, when you access  your  Network Connections, right click on your  network icon and choose Diagnose.

If none of above works, restart relevent physical switches and see

Do you always getting this problem, If so post we'll look @ it.

Prime