Simple Troubleshooting for AD / DNS

[u/BlueLining-Solutions]

**A simple troubleshooting sequence for AD/DNS symptoms**
When domain authentication, Group Policy or domain-controller discovery starts behaving inconsistently, I prefer to establish the basic evidence before making configuration changes.

My initial checks are:
ipconfig /all — confirm the configured DNS servers and network settings.
Resolve-DnsName _ldap._tcp.dc._msdcs.yourdomain.local -Type SRV — check whether the relevant domain-controller locator records resolve. Replace the example domain with your own.
nltest /dsgetdc:yourdomain.local — test domain-controller discovery.
dcdiag /test:dns — investigate DNS-related domain-controller health.
repadmin /replsummary — review replication failures and delays.
I treat these as a starting point rather than a definitive diagnosis. A successful DNS lookup does not rule out every DNS issue, and replication problems can have causes beyond DNS.
The important part is to preserve the output and correlate it with event logs, timestamps and recent changes before attempting a fix.
A repeatable evidence-first process makes troubleshooting easier to explain, reproduce and hand over. You opinion?

[u/Sad-Chapter-6007]

nltest and dcdiag catch like 90% of the weird auth issues I run into, the rest is usually some stale SRV record or a DC that lost its secure channel and nobody noticed

I'd add checking the time skew between clients and DCs, had a whole site fall over once because the PDC emulator drifted 6 minutes and kerberos started rejecting tickets, took way too long to find because all the DNS checks came back clean

keeping a running notepad of timestamps and what you ran before touching anything has saved my ass more times than I can count, especially when someone else changed something at the same time and you need to prove it wasn't you who broke it

[u/ludlology → u/Sad-Chapter-6007]

+1 for time - if it isn’t an outage or dns, it’s usually time