DCDiag is one of those command line utilities that you should turn to when you
have a Windows Server 2003 problem. As a source of Active Directory clues, DCDiag comes second only to the Event Logs. You may have guessed that the DC in DCDiag means domain controller.
Even if your Active Directory
appears to be running smoothly, it is still worth
running DCDiag, if only to learn about the components of a healthy operating system. For example DCDiag shows the existence of the knowledge consistency checker (kccevent).
With DCDiag it's not so much installing, as getting a copy from the Window Server 2003 Support tools. I could not help noticing that after I installed Windows Server 2003 SP1, there was a new
DCDiag with twice the file size. It reported to be version 5.2.3790.1830. Intrigued, I checked the old version and found it was 5.2.3790.0 (no 1830). Further research revealed that indeed, the
new version has more tests; as DNS is always a worry whenever there is an Active Directory problem, I was pleased to see Microsoft added extra DNS health checks in the latest version of DCDiag. (See bottom of this page
for a free copy of DCDiag.)
/v
I have to admit that at first I had no idea that DCDiag had switches. Whilst I should have known that Microsoft would provide switches, I had no idea that there were so many. I will let you into
another secret, I have never before know the /v (verbose) to be of any use. My point is that many utilities have this switch and normally I avoid it, but in the case of DCDiag the /v is a little gem,
which I use at every opportunity.
/q From the sublime /v you could go to the ridiculous /q which only report errors.
/s As always, '/s specifies the server, or in this case, the Domain Controller.
/fix
Fixes Service Principal Names (SPN) problems.
/f:logfile.txt Slightly confusing given that there is also a /fix switch. It works like the re-direct pipe (> filename.txt). Personally, I copy and paste from the command prompt, but if you
are more organized, then use /f:filename to output to a file.
/test: Confession time. I gave up with the /test, I just could not get it to filter the dns tests as advertised. I
consoled my self that you can always get the information by running the full test and just reading the parts that are of interest. However, I got the /test switch working perfectly with NetDiag,
therefore, is it
me or have Microsoft made a documentation error?
Guy Recommends: A Free Trial of the Network Performance Monitor
(NPM)
Solarwinds'
Orion performance monitor
will help you discover what's happening on your network. This
utility will also guide you through troubleshooting; the dashboard will
indicate whether the root cause is a broken link, faulty equipment or
resource overload.
Perhaps the NPM's best feature is the way it suggests solutions to network
problems. Its
second best feature is the ability to monitor the health of individual VMWare
virtual machines. If you are interested in troubleshooting, and creating network maps, then I recommend that you take advantage of Solarwinds' offer.
1) DCDiag has several useful switches. Actually the switches are an example of horses for courses, for example, if you only want to report on errors, then
enter /q. However if you want chapter and verse then /v is your best bet.
2)
Use the output as an opportunity to investigate services, for example 'The File Replication Service SYSVOL'. any problem with the frssysvol could alert you to Group Policy problems.
Syslog messages are full of information for troubleshooting network problems.
When something goes wrong then surely there will be an error message in the syslog datagram - if only we can find
that record and interpret the event. What will help to capture and analyze such
network messages is the Kiwi Syslog Server.
Guy Recommends: Orion's NPM - Network Performance Monitor
Orion's performance monitor is designed for detecting network outages. NPM makes it easy to see what's working, and what needs your attention.
This utility guides you through creating network maps. It also helps troubleshooting by indicating whether the root cause is faulty equipment, or resource overload.
