08-09-2018 06:05 AM
One of our customer is running an Infoblox HA pair configured as DNS/DHCP servers. These devices are authoritative for an AD domain. Name lookups and dynamic updates through GSS-TSIG are just working fine. No error show up in Infoblox log files. NIOS is version 8.2.
However, customer told me that when he types "dcdiag" command on any of his domain controller, the following error message shows up:
test: SystemLog * The System Event log test
An error event occurred. EventID: 0x0000272C Time Generated: 07/27/2018 11:13:08 Event String: DCOM was unable to communicate with the computer <Infoblox DNS/DHCP server VIP> using any of the configured protocols; requested by PID 177c (C:\Windows\system32\dcdiag.exe).
==> seems that dcdiag.exe wants to open a TCP/135 connection with the Infoblox server - which of course does not work.
I am now wondering why this is happening. DC are running Windows Server Standard 2012.
I set up a lab environment and could not reproduce the issue: dcdiag never tries to connect to an Infoblox DNS/DHCP server through TCP/135.
I opened a ticket at Infoblox support, they do not seem to have a clue either.
Does anybody here has a suggestion ?
Solved! Go to Solution.
08-13-2018 08:31 AM
You are correct in that there is no reason why the DC should be attempting to communicate with the DNS server on TCP port 135, which would be for RPC. Researching the event ID included in the event view log, I ran across the following:
This indicates that the issue might be related to the domain controller attempting to use IPv6 but this not being enabled at the NIC. If dcdiag is able to complete, I would ignore the error. This is simply an attempt to communicate to another server and that would be expected to fail as the other server in question is not a Windows system.
08-17-2018 01:55 AM
Thanks for your answer. I actually saw this article before. I will check with customer if this can be IPv6-related.