Right after New Years Eve I had to update some packages/advertisements for some new software. That was easy, but the problem was that none of the clients got the advertisements.
I started to troubleshoot the problem and looked at the ConfigMgr Site Status. There I got some really nasty errors one for the MP Control Manager component and another for the MCS Control Manager.
MP Control Manager detected management point is not responding to HTTP requests. The HTTP status code and text is 400, Bad Request.
MCS Control Manager detected MCS is not responding to HTTP requests. The http error is 400.
This was clearly an IIS error but I also knew that I had not messed up with the settings lately. I then checked if my MP site was accessible from a web browser. First I tried http://full_dns/sms_mp/.sms_aut?mplist but got .. Error 400 Bad request. Strange! I then tried with the local IP address (http://IP_Server/sms_mp/.sms_aut?mplist) of the server and that worked. I double checked the bindings in IIS, they were good – port 80 and 443 with the IP address of server. Next thing I decided to test was the DNS.
I pinged the full DNS of the SCCM server and bang it hit me .. I was getting back an IPv6 address. The reason for that is I decided to test DirectAccess in my network so I enabled IPv6 on all servers. And by default it would seem that IPv6 addresses take precedence over IPv4. Knowing this the solution was easy, just modified the binding in IIS to add the IPv6 address (All Unassigned works too).