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Archive for the ‘DNS/DHCP’ Category

DNS Resouces Repository

Posted by Awinish on April 9, 2013


Presuming, many of you are aware that DNS is the heart of the Active Directory(AD) & without proper DNS infrastructure it is not possible to design and setup good AD design. It is said that before mastering the AD, master DNS first because if you are able to setup DNS design perfectly, you have avoided most of the troubles for your AD.

I was searching for the some DNS information on the Technet & found a very useful link, which points considerable quality of the DNS resources. AT the right side of the page,  you can browse for Top DNS questions , recommendations for top the DNS issues,diagnostics etc. It also contains webcasts & useful videos for better understanding.

It includes resources for 2008 to 2003, tips for diagnosing DNS, designing, implementation etc.

Example

Windows Server 2008 R2 Resources

Domain Name System (DNS)

http://technet.microsoft.com/en-us/network/bb629410.aspx

 

Posted in DNS/DHCP | Tagged: | 2 Comments »

Configuring DNS in child domain

Posted by Awinish on April 9, 2011


I have seen people through various forums/blogs getting confused : how to configure DNS server in child domain for Parent’s domain name resolutions?  The confusion is, should it point to itself for DNS server address or parent DNS server for name resolution of parent & child domain both? In order to make the life easier & remove the confusion, i thought of coming up with the article on my blog.

Firstly, understand that DNS is the backbone of AD & most of the issues we face in our environment is because of the improper configuration of DNS server.  In few posts, i saw people using Public IP as the DNS address or ISP’s DNS address directly configured into their servers/domain systems NIC for preferred DNS server address, which is absolutely wrong & the reason is, when DNS lookup is performed against the local resource records in the domain, first it queries local host file in your system located in inside “etc” folder, if it can’t locate anything configured there, it looks for preferred DNS server IP in NIC. If NIC’s preferred DNS address is configured with public IP or ISP’s IP, it will forward the query directly to that public IP for local domain name resolution & the query will be performed, before it is says request timed-out. The reason is that, your local domain & its records exists in your local DNS server. How a DNS server hosted outside your domain can even come to know existent of any such private domain without any record in its DNS server? From security perspective, its a big passage for attacker to penetrate your infrastructure & attack your network for access.

Public DNS server’s IP has to be configured into Forwarder Tab of your local DNS server. If you have multiple DNS server running in your domain, configure all of the local DNS server forwarder to have this Public DNS IP address, but make sure you obtain this public DNS server address from your ISP & you are not using anything like 4.2.2.2 or 2.2.2.2/8.8.8.8, since these are not the authoritative DNS server for your domain through which query has to pass for name resolution. The query for external domain name resolution has to pass through your ISP’s DNS server. Using 4.2.2.2 or any other public IP directly in your DC/servers as a preferred DNS or alternate DNS server is going to pose a security threat for the environment.

Question: How do I set up DNS for a child domain?

Answer: To set up DNS for a child domain, create a delegation record on the parent DNS server for the child DNS server. Create a secondary zone on the child DNS server that transfers the parent zone from the parent DNS server.

Note Windows Server 2003 has additional types of zones, such as Stub Zones and forest-level integrated Active Directory zones, that may be a better fit for your environment.

Set the child domain controller to point to itself first. As soon as an additional domain controller is available, set the child domain controller to point to this domain controller in the child domain as its secondary.

http://support.microsoft.com/kb/291382

How To Create a Child Domain in Active Directory and Delegate the DNS Namespace to the Child Domain

http://support.microsoft.com/kb/255248

Note: Ignore the version of OS, its applicable for all the windows OS as concept for DNS has not been changed.

 

Posted in Directory Services, DNS/DHCP, Exchange | Tagged: , | 6 Comments »

Friday Mail Sack Directory Services by NedPyle(Technical Lead in Microsoft)

Posted by Awinish on March 25, 2011


Presuming, many of you know & its for them who don’t know, NedPyle(Technical Lead in Microsoft) shares his knowledge base on DS at every Friday known as Friday Mail sack questions/answer, which gives us best opportunity to learn about DS in depth & clear the doubts/myths related Directory services. It occurs on every Friday(if he is not on leave or any other reason)shares plethora of interesting concepts & facts on Directory services.

If you are eager to know the working, concepts, design, bugs etc. related to Directory services, keep an eye on Friday mail sack as well as NedPyle’s Blog on below link. I can say firmly it cleared lot of my doubts & enhanced my DS concept, if you wish to learn, do take a look or add it to your favorite space or use RSS feed, its worth reading & your time.

Its a great initiative by Ned & DS team. Kudos to Ned & his team for the great work.

Take a look at his latest session on Dcdiag.

http://blogs.technet.com/b/askds/

Friday Mail Sack

http://blogs.technet.com/b/askds/archive/tags/mail+sack/

 

Posted in Directory Services, DNS/DHCP, Exchange, OS/Certificates, SCCM/SCOM | Tagged: , | Leave a Comment »

DNS recommendations from Microsoft

Posted by Awinish on March 8, 2011


Many forum/post, often i see a question, how to configure DNS in my domain controller, is primary point to itself or secondary DNS server, is it OK to configure loopback IP & what are the best practices etc.

I would not cover everything, leave for the below link to answer for you. Few things, i would like to mention

  • NEVER use public IP configured directly in the NIC either of the DC or clients.
  • Public IP(ISP DNS) used for external domain name resolution,should always be configured in Forwarder of DNS servers.

NedPyle from Microsoft has got recommended & best practices for DNS. So next time you aare confused or looking for best practices follow the below link.

http://blogs.technet.com/b/askds/archive/2010/07/17/friday-mail-sack-saturday-edition.aspx

http://blogs.technet.com/b/askds/archive/2010/08/02/new-dns-and-ad-ds-bpa-s-released-or-the-most-accurate-list-of-dns-recommendations-you-will-ever-find-from-microsoft.aspx?PageIndex=2

 

Posted in Directory Services, DNS/DHCP, Exchange | Tagged: | 3 Comments »

DNS Scavenging And Auditing concepts

Posted by Awinish on February 8, 2011


Scavenging is the important process for removal of stale records from DNS to keep it healthy & fit. Lot of people have doubts, whether it has to be enabled or not & find themselves in confused situation what is exactly scavenging & how it works.

I have seen a question, if i create a  static records(created a record manually) will the static record is also be eligible for scavenging, the answer is no. The reason is when you create a static record the box in front to Delete this record when it becomes stale is unchecked(shown in figure), which is not the case with automatic record creation process.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

When any machine is disjoint from domain, its record is not been deleted instantly, but the  dnsTombstoned attribute is changed to TRUE & it is deleted from the DNS server in-memory cache. The scavenging process starts at 2AM everyday & compares the dnsTombstoned value is set for deletion or not.

DNS Scavenging internals (or what is the dnsTombstoned attribute) for AD Integrated zones

http://blogs.technet.com/b/isrpfeplat/archive/2010/09/23/dns-scavenging-internals-or-what-is-the-dnstombstoned-attribute-for-ad-integrated-zones-dstombstoneinterval-dnstombstoned.aspx

Don’t be afraid of DNS Scavenging. Just be patient

http://blogs.technet.com/b/networking/archive/2008/03/19/don-t-be-afraid-of-dns-scavenging-just-be-patient.aspx

It Takes Two–DNS scavenging

http://blogs.technet.com/b/dougga/archive/2012/02/09/it-takes-two-dns-scavenging.aspx

How to enable auditing of records creation, modification or deletion in DNS?

The above reason will suffice, the dns records are not deleted immediately, but dnsTombstoned attribute is changed either True or False for later deletion. So, if you plan to join the system into domain which is immediately been removed, you need to delete the records manually along with manually deleting computer object from ADUC to join the system into domain or wait for few hours to be done.Take a look at below link to know more.

http://blogs.msdn.com/b/anthonw/archive/2006/08/23/715983.aspx

I wanted to point out this wonderful article explaining duplicate dns zones, well written by Greg. I was pointed to this article by Mike Kline.

Am I Seeing Double? The case of “Multiple copies of the same DNS zone”

http://blogs.technet.com/b/askpfeplat/archive/2012/02/05/am-i-seeing-double-the-case-of-quot-multiple-copies-of-the-same-dns-zone-quot.aspx

 

Posted in DNS/DHCP | Tagged: , , | Leave a Comment »

Loopback Group Policy Explained

Posted by Awinish on November 11, 2010


Loopback group policy are used to apply user configuration settings on the computer. The loopback policy comes to rescue when you want to apply users configuration settings to the computer irrespective of what what users are login to the particular system.There is two mode basically one is Replace and other Merge mode.  When you select replace mode in the loopback GPO, computer and user configuration configured in that OU will be applied irrespective of the which OU user belongs to and what user configuration GPO has defined in that OU. When you select Merge mode, user and computer configuration configured in the loopback GPO as well as user configuration GPO for the user belongs to the different OU will be applied. In case of conflict user configuration from the loopback GPO will win.

http://social.technet.microsoft.com/wiki/contents/articles/windows-server-understand-user-group-policy-loopback-processing-mode.aspx

Loopback policy is very effective GPO setting, but it requires proper understanding & planning,before it can be implemented in the live environment. I always believe without proper understand or something new to be tried has to go via lab testing else your production environment will become testing environment and can cause serious business loss to the clients. For testing,create a independent lab which can be either using virtual PC or VMware software. Always, test the GPO before applying to the production because reverting the changes requires time and may not be as simple as applying.

Additional references to help you better understand.

http://technet.microsoft.com/en-us/library/cc782810%28WS.10%29.aspx

http://cbfive.com/blog/post/Demystifying-Loopback-Policy-Processing.aspx

http://kudratsapaev.blogspot.in/2009/07/loopback-processing-of-group-policy.html

 

Posted in Directory Services, DNS/DHCP, Group Policy | Tagged: , | Leave a Comment »