EMC 2010: The attempt to connect to using "Kerberos" authentication failed.

Last weekend I couldn't launch the EMC on an SBS 2011 server:

The solution?  The MSExchangePowerShellAppPool wasn't running.  Thank you, TechNet blog.

Invalid DNS server prevents RDP connections

A headless Hyper-V core server in my lab wouldn't accept RDP connections because it couldn't authenticate the incoming username due to an invalid DNS configuration on its NIC.

Connecting a monitor and keyboard would've been too easy

A remote Powershell session (authenticated as the server's local administrator) worked...

Enter-PSSession -ComputerName COMPUTER -Credential USER

...but sconfig wouldn't run.

Fear not, you can see your entire network configuration by running netsh dump.  To set the primary DNS server to 1.1.1.1 on my Server 2012 R2 host with a network interface called "vEthernet (External_Internal)":

netsh interface ip set dnsservers "vEthernet (External_Internal)" static 1.1.1.1 primary

When your domain controller has been offline for > 60 days

When trying to demote a domain controller which had been powered off for several months, I ran into this error:

Also, the new domain controller that I'd just spun up couldn't access the NETLOGON share.

DCDIAG had this warning:

The DFS replication event log had this warning, with instructions that don't work:

Thankfully, this blog post explained what to do (all on one line):

wmic.exe /namespace:\\root\microsoftdfs path DfsrMachineConfig set MaxOfflineTimeInDays=200