DNS netmask ordering

March 19th, 2014 No comments

One customer has two physical locations. Here is following IP setting for both locations:

Location 1 – IP range 10.0.0.0/23 and wpad server is 10.0.0.22

Location 2 – IP range 10.0.2.0/24 and wpad server is 10.0.2.22

When you create two same A records in DNS you get two IP addresses on DNS query. Order of DNS record is changing, because we have Round Robin enabled on our DNS servers. This is default behaviour.  Here is some testing with nslookup:

Same results were in both locations. What we wanted to achieve was that we need DNS servers to return IP address 10.0.0.22 in location Location 1 on first place and IP address 10.0.2.22 in location Location 2 on first place. To make it work we need to look on feature called netmask ordering on DNS servers. You can read more here.

Let’s transfer IP addresses in each location into binary:

10.0.0.0/23

00001010.00000000.00000000.00000000 — 00001010.00000000.00000001.11111111

10.0.2.0/24

00001010.00000000.00000010.00000000 — 00001010.00000000.00000010.11111111

Networks in both locations are same to 22 bit from begging. First different bit in 23rd. So we need to change netmask ordering on DNS server to use first 23 bits to compare when returning results to client. It means our netmask ordering has to be set to:

00000000.00000000.00000001.11111111 — 0x000001FF

We need to set it on all DNS server and restart DNS service:

Once we do this on server we can see following result in Location 1:

and following result in Location 2:

So now it’s all set and ready to go.

Have a great day,

Quickie: Tail in Powershell

February 28th, 2014 2 comments

There is lots of great tools in Linux which are needed in Windows environment. One of the great tool from linux is “tail”. You can use it following way:

tail -f /var/log/mail.log

You will get end of the file and you see all content added to file on screen. You can view log files without need to reopen it. In Windows I use utility Trace32.exe. I was looking for some more native way to do it in Windows. There is a cmd-let Get-Content in Powershell which you can use following way:

Get-Content C:\Windows\WindowsUpdate.log -Wait -Tail 10

This tails only 10 lines from the end of the file and “waits” for new added lines. Switch “Tail” is accessible only in PowerShell 3 and higher.

Powershell is getting there,

RemoteApp Name problem

February 26th, 2014 No comments

At one customer I have implemented RemoteApp on Windows Server 2012 R2. Clients connecting to RemoteApp were Windows 7. Everything worked fine besides one computer. When I launched RemoteApp from application provided automatically using Control Panel, I received following error (This RDP file is corrupted. The remote connection cannot be started.):

When I tried to run application using Web portal everyhing worked fine.

Names of the RemoteApp contained diacritics and name was displayed in bad form:

So I tried to disable all diacritics in RemoteApp names and everything started to work as it should.

Weird things are:

  • There are not limits defined on web for RemoteApp names
  • There are not errors logged anywhere with saying anything about “bad name” in RemoteApp

So remember not to have any other characters in RemoteApp names besides clasis english ones.

Have a nice day,

 

Moj prvý pokus o prezentáciu na ShowIT 2013

February 12th, 2014 No comments

Nech sa paci LINKA.

 

Categories: Microsoft, Windows Tags: ,

Moje prednášky pre ShowIT 2014

February 12th, 2014 No comments
Categories: Microsoft, Windows Tags: , , ,

Quickie: Exchang database migration over 24 hours

December 9th, 2013 No comments

Over the weekend I was setting up Exchange 2010 database copies using DAG. Those databases were huge (total of 3,5 TB). Line between primary and backup datacenter was 100Mbps. This migration ran over 24 hours for couple databases. When I checked the status I saw job was running 23 hours and 20 minutes:

When I have checked status in about hour and half I saw interesting time:

This happened on all databases which ran over 24 hours 🙂 So it looks like Microsoft engineers haven’t think about job running more than 24 hours 🙂

That’s all from weekend,

AVMA key in Hyper-V

November 26th, 2013 No comments

When you buy Windows Server 2012 R2 Datacenter edition you don’t have to activate every Windows Server 2012 virtual machine (Windows Server 2012 R2 Datacenter, Windows Server 2012 R2 Standard or Windows Server 2012 R2 Essentials.). There is new license key for Windows. It’s called Automatic Virtual Machine Activation (AVMA). You have to active Hyper-V host operating system. Then you use one of following AVMA keys for VMs on your Hyper-V hosts:

Datacenter Y4TGP-NPTV9-HTC2H-7MGQ3-DV4TW
Standard DBGBW-NPF86-BJVTX-K3WKJ-MTB6V
Essentials K2XGM-NMBT3-2R6Q8-WF2FK-P36R2

You use this keys using elevated command prompt on VM:

slmgr /ipk <AVMA_key>

When you do all of these steps all your Windows Server 2012 will be automatically activated. Even without  access of Internet from VM.

I hope something similar will be deployed on VMWare virtualization.

More oficial from Microsoft here.

Categories: Microsoft, Windows Tags:

Quickie: Nice utility to check DNS in AD

November 19th, 2013 No comments

Where there is a problem with AD replication, there is most of the time problem with DNS. Most of the time there are bad DNS records or missing DNS records. There is cool utility to check DNSLint.exe from Microsoft. It is designed to do all manual check I do when trying to solve AD replication problems.

You can download it from here and also read more about it.

It’s bad it’s not included into operating system by default.

Quickie: Delete all Offline files on Windows XP

November 19th, 2013 No comments

Couple days ago I migrated fileserver. We moved redirected My Documents for users on another server. We also hided these shares behind DFS namespace to make it more manageable in future. But we found out problem with this setup –  offline files. Windows XP kept offline copies of old and new redirected files. We had to clean this offline data database. I setup start up script:

@ECHO OFF
IF EXIST C:\OfflineFilesClean.txt (
  REM Do one thing
) ELSE (
  reg.exe add “HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\NetCache” /v FormatDatabase /t REG_DWORD /d 1 /f
  echo Vymazane > C:\OfflineFilesClean.txt
)

This script was dedicated just for Windows XP, so I had to apply GPO using WMI filter:

SELECT * FROM Win32_OperatingSystem WHERE Version LIKE “5.1%” and ProductType = “1”

This script would work also on Windows 7 and Windows 8, but those OS didn’t have problem.

That’s all for today,

Quickie: When you disable Data Decuplication you will lose Shadow Copies data

October 22nd, 2013 No comments

We had some problems with backup system backing up Windows Server 2012 deduplication enabled volumes. We decided to disable Data Deduplication on volume. After volume was converted back into “non data deduplication mode”, we found out that all Shadow Copies meta data was lost. It means all “Previous Versions” were lost. I really don’t see any reason to act like that, but there is probably some. It would be great if Windows warns you before you do the change. But it doesn’t 🙂

Have a nice day,