Long DHCP lease causes client’s DNS name to disappear

Recently, we found that some servers’ and workstations’ host record (A RR) has been dropped off our DNS servers. All the machines were running a DHCP clients and we are using MS product for both DHCP and DNS.

The DHCP servers are configured to update the host record on behalf of the client. When we checked the scopes, we found that they have a 30 days lease duration. Very quickly it was established that its possible that the host records could have gone stale in the DNS due to the lease duration and got scavenged.

A quick chat with our DNS team and we found our that the DNS servers have a setting of about 14 days before a record is scavenged in a daily routine. Namingly the values are 7 days for non-refresh interval and 7 days for refresh interval.  (see DNS Aging/Scavenging Simplied)

NICs causing Windows start up issue on quad core CPUs

We had a bunch of HP Proliant DL580 G5 running with 4 x quad core CPUs. With all the cores turned on, this would give us 16 CPUs. When trying to build the servers into Window 2003, we found that Windows startup page (the one with the moving bar at the bottom) would hang and not continue.

After some trial and error, we found that if we disabled “”one-half of cores per Physical Processor” from the BIOS (effective with 8 CPUs), the server would then boot up correct. So we continued with the Windows build and completed building the servers into 32-bit Windows 2003 Enterprise Edition.

Windows 2000 terminal services which stopped working

We were doing a round of upgrades in our Windows estate and we found that one of the Windows 2000 server had a broken terminal service.

All the following checked out, but the server was just not listening on port 3389:

• terminal services is running (reboot server like a gooogle times) and not error in eventlogs
• no other applications is locking 3389 preventing it from being used
• no ipsec policies was set
• no ipfilter was configured.
• when I run tsadmin on the server (obvious remotely won’t work),  I could see my only session

CPU issue causing BSOD 7F (0×0D, 0×00, 0×00) & 9C (0×00,xxx,xx,xx)

We had a strange server that would BSOD regularly with stop codes 7F or 9C, in the later days it was BSODing every 10 mins or so.

So we had the motherboard change and it stop BSODing for about 1 hour and started again!

Diagnostics was ran but all were successful (how typical!) and HP was really reluctant to bring down other parts as the diagnostics showed okay. In fact, this is not the first time I have seen HP servers with good diagnostics but after changing on of the parts, everything is resolved.

Windows 2000 cannot startup with message “loader error 3

Recently we were going through a upgrade exercise for our entire Windows estate to patch them to out latest security and company specific components. We encountered, so far, two servers that when rebooted, Windows 2000 will not start up and they showed this error

Windows 2000 could not start because of an error in the software. Please report this problem as Loader Error 3.

Starting up in recovery console or safe mode is no hope as we encountered the same error. So this points to a fundamental issue with the Operating System.

VBScript: nth Day of the month

Recently I needed a function to calculate the nth day of the month, that is, first sunday, 2nd thursday, last friday, etc. I thought such functions would be easy to find in the internet, however, I couldn’t find a complete function and so decided to write one:

Apologise for the formatting, wordpress don’t like programming codes in their blogs

SMB2: What’s new?

2 interesting article exploring new SMB2 and performance improvements

http://blogs.technet.com/josebda/archive/2008/11/11/file-server-performance-improvements-with-the-smb2-protocol-in-windows-server-2008.aspx

http://blogs.technet.com/josebda/archive/2008/12/05/smb2-a-complete-redesign-of-the-main-remote-file-protocol-for-windows.aspx

MS08-067: MS sneezes, Windows Admin have to work overtime

I am sure most of the IT guys supporting Windows out there would have been impacted by the release of the RPC patch, MS08-067: Vulnerability in Server service could allow remote code execution.

This has caused a flurry of activities with the top management in my firm with over night meetings and engineering trying to churn out the fix that can be deployed globally and top honchos deciding the best way to deploy this globally and have the servers rebooted.

WINS: Stumped (temporarily) by lmhosts (again…)

We had a issue yesterday when we cannot logon an old Windows NT server using our domain (let’s call it DOM1) account. The NT server is actually one of those leftover legacy NT domain BDC (lets call it RES1) that has trust to DOM1.

DOM1 was only upgrade to Windows 2000 AD last weekend and all access were tested successfully. Come Monday, apps team complained that they cannot logon with their DOM1 account to the NT server.

Our first thought is it has lost trust to the upgraded DOM1 domain, but we checked the PDC for RES1 and it was okay and this server (which is the BDC) was in sycn with the PDC in RES1.

MSCluster: Low free PTEs caused cluster service to disconnect

Back in the days when a lot of us are not sure what the 3GB switch really does and thought its must be set so that Windows can recognise 4GB RAM and above, a number of our application servers has been set with 3GB switches in their servers. This is one of the servers.

The other day one of the application cluster suddenly failed over. A quick check on the servers’ eventlogs show not issues with low non-paged pool memory or memory issues nor any network issues. The application logs was rather clean, other than a strange repetitive event from the MOM agent. We have a keep alive event which the MOM agent runs once a day, but I was seeing the same event running 2 twice every minute. On another server when had the same program we could see that the idling node had cpu running at 20% or more. Once we stopped the MOM agent, the cpu dropped to almost idle.