PROD IMMs ACCESS Failed:

I can not access IMM.
 
Here’s what we’ve tried so far:
1.            Normally can access the IMMs from browser (once connected to network – but the GUI does not always come up for either IMM1 nor IMM2.
2.            The IMMs on PROD2 are fine.
3.            Cannot telnet nor SSH to the IMMs either.
4.            I can ping the IMM IP addresses from the switches, so I think the mgmt network to them is okay…and can get to the AMMs on the same frame.
5.            I rebooted one of the M4s and that did not change the issue.  The access came back on its own.
 
I saw the following message in the IMM web interface when he navigated to IMM Management > Network:
 
The IMM2 is assigned a static IP address. When using a hostname or FQDN (Fully Qualified Domain Name) , at least one DNS (Domain Name System) server must be specified in DNS tab and make sure the DNS server can resolve the hostname or FQDN to the IP address. Otherwise, communication errors will occur.
 
I don’t want to assume this is the issue, but perhaps some investigation could be done.

Any ideas/ comments/ feedback to troubleshoot this issue would be highly appreciated.

Is it a layer 3 switch? Post the routing table and the arp table. 

"route -n" or "show route" or "show arp" or "show ethernet switching-table" whichever is close to your switch CLI.