DFS Replication Validation Script…

The other day, while at the enterprise-level customer with whom I’m currently working, I ran into a situation where I needed to validate that certain parts of a DFS hierarchy were properly being replicated across the customer’s AD domain controllers.  As the administrators applied normal, routine DFS changes, the changes sometimes didn’t replicate properly across the enterprise — causing some segments of the DFS structure to not be visible or available. 

Apparently, the DFS problem was a result of using VMware guests as AD DCs.  I understand (from the customer) that a Microsoft hotfix is in the last stages of testing (at the time of this writing) and will be available for release “soon.”   It seemed that even though the DCs in question did not synchronize time with the ESX host upon which they reside, there is a default behavior in VMware Tools that assigns the host time value to the guest — at least up until the “do not sync” routine is processed during startup; after which the guest is then allowed to find its own time.  During this brief time window, the DFS Namespace service sometimes completes assembling its DFS target list and can find itself behind in time, relative to links it has been given by PDCE; which makes no sense to it, and it removes them from its listing.  And as a result, people can’t find their mapped drives or browse some of the DFS Tree.  (Note: I cannot take credit for this timing behavior investigation and results; and while I’d love to credit the folks who are due, I’m not permitted to.)  The customer remedied the situation with a temporary fix, but the real fix is the up-coming aforementioned patch.

Anyway, while the symptoms were being analyzed, I was working on other things and needed to work around the issue as much as possible while the solution was being chased.  So, I whipped up a simple little DOS script to go out and validate the top-levels of the DFS hierarchy across all domain controllers that carry them, in order to find out what would or wouldn’t be properly resolved.

For what it’s worth, I thought I’d pass the script along to you.  Here it is:


@set AdDomain=MyAdDomain.local
@set DirQuantity=17
@set DestPath=h:DcList.txt
@REM This requires elevated credentials, otherwise will fail...
@ipconfig /flushdns
@REM First we build the input file...
@nslookup %AdDomain% |findstr 
[0-9].*.[0-9].*|findstr /V /C:"Address: " > %DestPath% @ECHO As of 20121212, there should be %DirQuantity% DFS dirs on each server (actual, plus the "." and ".." items). @REM Now loop through the input file and check the DFS at the destination... @For /F "tokens=*" %%Q in (%DestPath%) Do @( @set MYDC=%%Q @set MYDC=!MYDC:Addresses: =! for /f "tokens=* delims=" %%A in ('dir /A:D \!MYDC!Corp ^|findstr /C:"Dir(s)"') do @set MYDIR=%%A for /f "tokens=* delims= " %%G in ("!MYDIR!") do @set MYDIR=%%G @REM Options A: Use this line if you wish to see all DFS sources: @ECHO For: !MYDC! !MYDIR:~0,9! @REM Option B: Use this line if you wish to see only those in violation @REM (note: there's a space and tab separator for spacing alignment): @REM @ECHO For: !MYDC! !MYDIR:~0,9! |findstr /V /C:"%DirQuantity% Dir(s)" )

What it does:

The script builds a domain controller list in a static, external file, then iterates through the list, attempting to quantify the available DFS path branches against a numeric count that you supply in another variable.  I provided two different “ends” to the script (one of them commented out), in order to give you a couple different ways to present the results.  Make sure to “set” the variables in the first few lines, to your locally-relevant information; especially the number of *expected* DFS hierarchies.

Of course, I wanted to write it to do more, but I pretty much ran up against the limits of what I *should* do in a DOS script.  I’ll make another version in PowerShell some day that iterates down the hierarchy and validates the entire structure, instead of just the top level… 

…Unless you beat me to it…  😉

There you go; enjoy!




2017-07-27T00:01:04+00:00 December 12th, 2012|Uncategorized|

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About the Author:

Jeremy is just a regular guy that likes to occasionally tell the world about stuff.