What DNS Zone type should I use, a Stub, Conditional Forwarder, a Forwarder, or a Secondary Zone?? What’s the Difference??

By Ace Fekay
Originally Published 2012
Updated 3/20/2018

Intro

Ace again. DNS is a basic, yet important requirement that many still having problems wrapping their head around it.

Besides design, a huge part of DNS is understanding the differences between the zone types. Many have asked, when do I use a Stub zone, a Conditional Forwarder, or a Forwarder? Or better, what’s the difference?

I thought to put this simple comparison together compiled from past posts in the TechNet Forum.

Partner Organization DNS Resolution: What should I use, a Stub, Conditional Forwarder or Forwarder?

Secondary Zone

Secondary zones are read only copies “copied,” or “zone transferred” from a Master zone. This makes the zone data available locally (as read only, of course), instead of querying a DNS server across a WAN link. However, in many cases Secondaries are not used due to many limitations and security concerns, such as exposing all DNS zone data that a partner may not want to divulge.

In addition, Secondaries can’t be AD integrated, and the zone data is stored in a text file. So you would have to manually create a copy on all of your DNS servers.

Stub Zone

Organizations own their own AD zones. When business partners need to resolve data at a partner’s organization, there are a few options to support this requirement. Years ago, prior to Stub or Conditional Forwarders, there weren’t many options to handle this other than to use Secondary Zones and keep copies of each others zones via zone transfers.  While the solution worked well in regards to name resolution, it was not the best security-wise, due to trust level between partners, because zone data is fully exposed at the partner. This became a security concern because the partner is able to see all of their business partner’s records. When the zone was transferred to partners, who knows what they were doing with the information. If the information was made public, attackers would have a field day with all of the IPs for the networked devices.

When stub zones were made available, it became a solution to overcome this security issue. What is also beneficial about Stubs, is you can AD integrate them instead of manually creating a Stub on each individual DC. This way the zone will be available domain or forest-wide, depending on replication scope.

However, some may say due to the fact that the SOA records are included in the zone file, it may be a concern that the SOA and NS data is exposed. In such high security concerns, the better solution would be to use a Conditional forwarder.

Conditional Forwarder

This option is heavily used, and many look at them as the best regarding security concerns with zone data exposure, because no data is exposed. This option has worked very well in many environments.

With Conditional Forwarders, no information is being transerred and shared. The only thing you would need to know is one or more of your business partner’s DNS server IPs to configure it, and they don’t have to be the SOA, rather any DNS server that hosts the zone or that has a reference to the zone.

However, it does require open communication and let each other know when their DNS server IPs may change, because you must manually set them.

Windows 2003 introduced Conditional Forwarders, but it did not have the option to make it AD Integrated. If you have 10 DNS servers, you must create the Conditional Forwarder on each server manually. The AD integrated option was added to Windows 2008 or newer DNS servers, so you don’t have to manually create them on each DNS server. THis way the Conditional Forwarder will be available domain or forest-wide.

Parent-Child DNS Zone Delegation

Delegation can be used in a situation where a child domain host their own DNS zone.  Therefore in the forest root domain, you would create a delegation zone with the IPs of the DNS servers in the child domain.  This is normally performed when the child zone have their own administrators. It’s also useful they do not have access to “see” all of the forest root DNS records.

Summary

I hope this helps! If you have any questions, and I’m sure you do, please feel free to reach out to me.

Major revision – Published 3/20/2018

Ace Fekay
MVP, MCT, MCSE 2012, MCITP EA & MCTS Windows 2012|R2, 2008|R2, Exchange 2013|2010EA|2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP – Mobility

As many know, I work with Active Directory, Exchange server, and Office 365 engineer/architect, and an MVP in Active Directory and Identity Management, and I’m an MCT as well. I try to strive to perform my job with the best of my ability and efficiency, even when presented with a challenge, and then help others with my findings in case a similar issue arises to help ease their jobs. Share the knowledge, is what I’ve always learned.

I’ve found there are many qualified and very informative websites that provide how-to blogs, and I’m glad they exists and give due credit to the pros that put them together. In some cases when I must research an issue, I just needed something or specific that I couldn’t find or had to piece together from more than one site, such as a simple one-liner or a simple multiline script to perform day to day stuff.

I hope you’ve found this blog post helpful, along with my future scripts blog posts, especially with AD, Exchange, and Office 365.

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Complete List of Technical Blogs
https://blogs.msmvps.com/acefekay/

This posting is provided AS-IS with no warranties or guarantees and confers no rights.


 

Active Directory DNS Single Label Names

Intro

Hey everyone, Ace again. Let’s discuss this issue. I hardly see this issue any more, because it was a previously prevalent when Active Directory was introduced, since there were some confusion about AD domain naming, and many IT admins used NT4’s domain naming guidelines. Man of us are now familiar with AD’s naming convention, and have more than likely renamed or rebuilt their AD domains. However, there are still some installations with this issue. 

How did it happen? Many reasons, such as lack of research on AD’s DNS requirements, assumptions, or a simple typo when originally upgrading from NT4 or promoting your new AD domain. It doesn’t matter now, because you were brought here to find out what to do with it.

I hope you find this blog informative on this issue and what to do about it.

First, let’s discuss a little background on the necessary components at play…

FQDN

First, let’s discuss the FQDN. What is an FQDN? It stands for “Fully Qualified Domain Name.” It is multi-level, or hierarchal, such as:

domain.com
domain.net
domain.local
childdomainname.domain.local
etc

What is a Single Label DNS Domain name?
The name is reminiscent of the legacy style NT4 domain NetBIOS domain names, such as:

DOMAIN
CORP
COMPANYNAME
etc

Unfortunately, since this does not work with DNS, and Active Directory relies on DNS, therefore, it does not work with Active Directory. Stay with me. I’ll explain…

DNS

DNS is a hierarchal database. Some call it a “tree” with a root (the ‘com’ or ‘net’, etc, name), then the trunk (the ‘domain’ portion of it), and the branches (such as www, servername, etc). The Root domain name, such as com, edu, net, etc, is also known as the TLD (Tope Level Domain name).

Basically you can look at a DNS domain name as having multiple levels separated by periods. The minimal requirment for an FQDN domain name, such as microsoft.com, is two levels. Then of course are your resource names, such as www, servername, or even child domain names under it.

Notice with a single label name there is only one name for the domain, or one level? Don’t get this confused with the NetBIOS domain name, that we were familiar with in the NT4 days. AD supports the NetBIOS domain name as well, but only as a NetBIOS domain name. It’s one of the domain names chosen when a machine is promoted into a domain controller for a brand new domain in a brand new forest. NT4 wasn’t reliant nor did it use DNS for NT4 domains. However, AD is reliant, therefore it must follow DNS naming rules.

Unfortunately the old NT4 style names are not hierarchal because there is only one level.
 
Since AD requires and relies on DNS, and DNS is a hierarchal database, a single label name does not follow any sort of hierarchy. DNS fails with single label names. Windows 2008, Windows 2003, XP and Vista have problems resolving single label names because it does not follow the proper format for a DNS domain name, such as domain.com, etc.

Also, Windows 2000 SP4 and all newer machines have problems querying single label names. It’s explained below by Alan Woods. Because clients query DNS for AD resources (domain controller locations and other services), they may have difficulty finding resources.

How did it happen? As I said earlier, it doesn’t matter now, because you were brought here to find out what to do with it.

Common Mistakes When Upgrading a Windows 2000 Domain To a Windows 2003 Domain (or any AD upgrade or installation):
http://support.microsoft.com/kb/555040

Single Label Name Explanation

Another variation of the Single Label Name explanation that I had provided in a response to a post in the DNS and/or AD newsgroups at one time:

The issue is the single label name. Locally at HQ, it’s using NetBIOS to join, however remotely, it’s relying on DNS. DNS queries do not work properly with single label names on Windows 2000 SP4 and all newer machines.

Period. Why? good question. It’s based on the fact DNS is hierarchal. Hierarchal meaning it must have multi levels, a minimum of two levels.

The TLD (top level domain) is the root name, such as the com, net, etc., names. The client side resolver service algorithm (which is governed by the DHCP Client service which must be running on all machines, static or not),
relies on that name for the basis to find the second level name (the name “domain” in domain.com, etc.). If the name is a single label name, it thinks THAT name is the TLD.

Therefore it then hits the Internet Root servers to find how owns and is authoritative for that TLD.Such as when looking up Microsoft.com. It queries for the COM portion, which the roots return the nameservers responsible for the COM servers, then it queries for the servers responsible for Microsoft.com zone.

If it’s a single label, the query ends there, and it won’t go further. However what is funny (sic) is that even though the single label name is being hosted locally in DNS, it will NOT query locally first, because it believes it is a TLD, therefore goes through the normal resolution (recursion and devolution) process, which causes excessive query traffic to the internet Root servers.

How to fix it? Good question. Glad you’ve asked.

  1. The preferred “fix” (in a one line summary), is to install a fresh new domain properly named and use ADMT to migrate user, group and computer accounts into the new domain from the current domain.
  2. An alternative is to perform a domain rename, (difficulty depends on the operating system and which version of Exchange is installed).
  3. As a temporary resort, you can use the patch or band aid registry fix to force resolution and registration that is mentioned in the following link. This must be applied to every machine. Unfortunately it must be done on every machine in the domain, including the DCs, member servers, workstations and laptops.

Information About Configuring Windows 2000 for Domains with Single-Label DNS Names:
http://support.microsoft.com/?id=300684

Single Label Names and being a better Internet Neighbor

The following was posted by Microsoft’s Alan Woods in 2004:

Single label names, from Alan Woods, [MSFT], posted:

—– Original Message —–
From: “Alan Wood” [MSFT]
Newsgroups: microsoft.public.win2000.dns
Sent: Wednesday, January 07, 2004 1:25 PM
Subject: Re: Single label DNS

Hi Roger,

We really would prefer to use FQDN over Single labled. There are
alot of other issues that you can run into when using a Single labeled
domain name with other AD integrated products. Exchange would be a great
example. Also note that the DNR (DNS RESOLVER) was and is designed to
Devolve DNS requests to the LAST 2 names.

Example: Single Labeled domain .domainA
then, you add additional domains on the forest.
child1.domainA
Child2.child1.domainA

If a client in the domain Child2 wants to resolve a name in domainA
Example. Host.DomainA and uses the following to connect to a share
\\host then it is not going to resolve. WHY, because the resolver is
first going to query for first for Host.Child2.child1.domainA, then it
next try HOST.Child1.domainA at that point the Devolution process is
DONE. We only go to the LAST 2 Domain Names.

Also note that if you have a single labeled domain name it causes excess
DNS traffic on the ROOT HINTS servers and being all Good Internet Community
users we definitely do not want to do that.   NOTE that in Windows 2003,
you get a big Pop UP Error Message when trying to create a single labeled
name telling you DON’T DO IT.  It will still allow you to do it, but you
will still be required to make the registry changes, which is really not
fun.

Microsoft is seriously asking you to NOT do this.  We will support you but
it the end results could be limiting as an end results depending on the
services you are using.

Thank you,

Alan Wood[MSFT]

 

Related Articles – Even though they seem old, they STILL APPLY!!!

Common Mistakes When Upgrading a Windows 2000 Domain To a Windows 2003 Domain
http://support.microsoft.com/kb/555040

Best practices for DNS client settings in Windows 2000 Server and in Windows Server 2003:
http://support.microsoft.com/kb/825036

DNS and AD (Windows 2000 & 2003) FAQ:
http://support.microsoft.com/kb/291382

Naming conventions in Active Directory for computers, domains, sites, and OUs (Good article on DNS and other names)
http://support.microsoft.com/kb/909264

============================================================

Summary

I hope this helps!

Published 10/15/2016

Ace Fekay
MVP, MCT, MCSE 2012, MCITP EA & MCTS Windows 2008/R2, Exchange 2013, 2010 EA & 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP – Directory Services

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Complete List of Technical Blogs: http://www.delawarecountycomputerconsulting.com/technicalblogs.php

This posting is provided AS-IS with no warranties or guarantees and confers no rights.

Event ID 5774

 

 

In general, these events indicates that the machine is unable to register its records with the DNS serverSleeping half-moon it’s configured.

Possible causes:

  • An ISP’s DNS server, or the router’s IP address, is set to be used as a DNS server in NIC properties.
  • The AD zone is configured to not allow dynamic updates.
  • If the 1st DNS entry is in another site, a firewall may be blocking necessary traffic.
  • Altered default security settings on the zone.
  • Altered default security settings in AD.
  • Altered default security settings on C: drive or C:\Windows folder.
  • Antivirus not configured to allow domain communications and services exceptions. See the antivirus vendor documentation on how to configure DCs for exclusions.
  • If the zone is set to Secure Only, possible Kerberos authentication errors will prevent registration. Causes of Kerberos errors can be numerous including misconfigured time service and antivirus exclusion, using an ISP’s DNS, third party installed firewalls or AV, and more.

Note on Firewalls

Active Directory communications require over 29 ports to be allowed, plus the ephemeral ports, and differ among operating system versions:

  • Windows 2003, Windows XP and older: UDP 1024 – 5000
  • Windows 2008, Windows Vista, & newer: UDP 49152 – 65536

DNS updates require TCP 53 & UDP 53, not just TCP 53.
It can be extremely challenging to configure a firewall for AD communications/ General rule of thumb is to just allow all traffic between locations.

Here’s a good list of the ports:

Active Directory Firewall Ports – Let’s Try To Make This Simple (RODC, too)
http://msmvps.com/blogs/acefekay/archive/2011/11/01/active-directory-firewall-ports-let-s-try-to-make-this-simple.aspx

If you need to control the ports AD uses across a firewall:

Active Directory Replication over Firewalls
http://technet.microsoft.com/en-us/library/bb727063.aspx

Paul Bergson’s Blog on AD Replication and Firewall Ports
http://www.pbbergs.com/windows/articles/FirewallReplication.html
http://www.pbbergs.com/windows/articles.htm

Restricting Active Directory replication traffic and client RPC …Restricting Active Directory replication traffic and client RPC traffic to a … unique port, and you restart the Netlogon service on the domain controller. …
http://support.microsoft.com/kb/224196

How to restrict FRS replication traffic to a specific static port – How to restrict FRS replication traffic to a specific static port … Windows 2000-based domain controllers and servers use FRS to replicate system policy …
http://support.microsoft.com/kb/319553

 

You can run the following tests on AD to ensure there are no errors:

  • DCDIAG /V /C /D /E /s:yourDCName > c:\dcdiag.log
  • Netdiag.exe /v > c:\netdiag.log (Run only on each Windows 2003 or older DCs, not 2008 or 2008 R2)
  • repadmin.exe /showrepl dc* /verbose /all /intersite > c:\repl.txt
  • ntfrsutl ds domain.com > c:\sysvol.log

Possible solutions:

  1. On the machine logging the above event, in their TCP/IP configuration, make sure they’re not configured for the same DNS server for both Primary and Secondary.
  2. The following registry value is incorrect: “SiteCoverage” under:    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
        This value typically should equal the domain name.
  3. You can try to flip the zone types to reset default settings.
    1. Change the zone type from Active Directory integrated to “Standard Primary”, then stop & start DNS.
    2. Then stop & start the netlogon service on the child DC & verify that the records are registered.
    3. If verified, then change the zone type back to Active Directory integrated and verify that the DC no longer records the Event log errors when the netlogon service is stopped & started.
  4. Make sure the machine logging the above event is pointing to a DNS server that support Dynamic updates and is hosting a zone for the domain (i.e. make sure it’s not pointing to the ISPs DNS server).
  5. Verify if there is no manually created CNAME, A or other record) for the same hostname. If there is, it will prevent the DCs from dynamically registering its host and you need to remove the manually created record.
  6. In a Parent – Child delegated scenario, and Event ID 5774 was logged on the domain controllers in the child domain:
        Setup:
        On the parent DNS servers, there is a delegation for the child DNS servers. The child DNS servers have forwarders up to the parent DNS servers.
        Cause and Fix:
        On the Security tab in the delegations, check if  “Authenticated Users” is missing.
        Added “Authenticated Users” and enabled Full Control.

References:

Domain Controller Generates a Netlogon Error Event ID 5774
http://support.microsoft.com/?id=284963

A DNS Update is recorded as failed: Event ID 5774, 1196, or 1578
This problem occurs when you use a third-party server application for DNS resolution. This includes SCCM causing false alarms, and cluster resources not initiating using a third party DNS server.
Hotfix available for Windows Server 2008 R2 or Windows 7.
http://support.microsoft.com/kb/977158

Event ID: 5774 Source: NETLOGON
http://eventid.net/display.asp?eventid=5774&eventno=353&source=NETLOGON&phase=1

Other References:

Technet thread: “Event 5774, NETLOGON” Friday, November 20, 2009
http://social.technet.microsoft.com/Forums/en/winserverNIS/thread/0507f7cc-c426-439b-a0c6-d36cda2dfee8

Technet thread: “Netlogon event 5774” Tuesday, February 01, 2011
http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/cf5c1e9e-dccb-45e2-9f14-144f8ba1f838/

================================================

Summary

I hope this helps with figuring out and fixing an Event ID 5774. 

Ace Fekay
MVP, MCT, MCSE 2012, MCITP EA & MCTS Windows 2008/R2, Exchange 2013, 2010 EA & 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP – Directory Services
Complete List of Technical Blogs: http://www.delawarecountycomputerconsulting.com/technicalblogs.php

This posting is provided AS-IS with no warranties or guarantees and confers no rights.

How to Create a Delegated Subnet Reverse Zone

You really, really want to host your public DNS records? If you do, you may also want to host your public IP range, instead of having to call your ISP every time you need a reverse (PTR) entry created or updated.

The key thing is setting the NS records in your zone file to the nameservers that are authorative for the zone based on ARIN and remove all iterations of your own nameservers.

Follow the syntax to create the delegated subnetted zone by using the syntax for “Child subnetted reverse lookup zone file” in the following article. But you must keep in mind, this MUST be done using a Standard Primary zone, so if it’s an AD Integrated zone, you must revert it to a Standard Primary zone so you can work on the zone files. Once you’re done you can change it back to AD Integrated, if you so desire.

How to configure a subnetted reverse lookup zone on Windows NT, Windows 2000, or Windows Server 2003
http://support.microsoft.com/kb/174419

Let’s try this example:

IP Subnet example: 192.168.10.160/27 (or 255.255.255.224)
IP Subnet Range:   192.168.10.160 to 192.168.10.191

If you take a look at that KB article I posted, it shows the exact steps needed to create it. That’s how I did it!

Let’s see if I can do it for your subnet range. I am not guaranteeing it will work, because it’s also reliant on how your ISP has it delegated.

Your IP subnet,  192.168.10.173 /255.255.255.224, indicates it is part of a range starting with 192.168.10.160 to 192.168.10.191, which give you 32 addresses in the range, 30 usable, assuming one is of course the router (gateway), which makes it 29 usable IPs.

Therefore, if this range was delegated to you, then the key IP to look at, which actually “Describes” the network block, as 192.168.10.160/27 or 192.168.10.160/255.255.255.224.

Based on the above:

Let’s run through the steps…

  1. Ask the ISP to delegate the subnetted zone, 192.168.10.160/27 to your hostname servers (you need two of them).
  2. Then to create the zone name, we must base it on your subnet starting IP and the subnet bit count.
  3. The IP subnet is  192.168.10.160/27
              The starting IP of this subnet = 192.168.10.160
              The bit count of this subnet = 27
    Therefore the syntax will be:
              <SubnetStartIP>-<SubnetBits>.10.168.192-in-addr.arpa
               OR
              160-27.10.168.192.in-addr.arpa.dns zone
  4. Based on that, create an ARPA (reverse) zone called 160-27.10.168.192.in-addr.arpa.dns zone.
  5. Then save it as a Standard Primary Zone (not an AD Integrated zone).
  6. Stop the DNS Server Service – In the DNS console, right click the server name, choose Stop.
  7. Then go into the file (system32\dns folder), and change all NS iterations from your server.InternalDomainName.com to the ISP’s. such as ns.ISP’sAuthorativeServer.com.
    (Please read the KB article for more information on how the zone file should be configured.)
  8. Save the file.
  9. Then Start the DNS Service – In the DNS console, right click the server name, choose Start.
  10. Then right-click the zone, choose Reload.
  11. Then right-click the zone, properties, Nameserver tab, remove your own server as an NS record only keeping the authorative server.
  12. Create a PTR record, such as for 192.168.10.173, under the zone, and call it whatever you want, such as ace.WhateveYourZoneNameIs.com.

Test it

Run nslookup or DIG to test a query to 192.168.10.173 internally and trying it using an external public nameserver.

If it doesn’t work, go through the above steps again. Follow the syntax EXACTLY.
If it does work, pour yourself a cold one.

 

References:

Technet Thread: “How to setup a Reverse lookup zone on windows 2008 server with IP address 65.19.134.173 and subnetmask 255.255.255.224.”
http://social.technet.microsoft.com/Forums/en-US/winserverNIS/thread/7c81a129-efa2-4b88-80bb-591c4119beb4/

Thread title: “Reverse DNS smaller than /24 (v4)”
 http://social.technet.microsoft.com/Forums/en-US/winserverNIS/thread/4147e8fe-43d8-4eff-a890-a0e1e31a96ea/#bd664835-05b3-4d53-9b08-d845b177d9d2

 

By Ace Fekay

Comments are welcomed.

Ace Fekay, MCT, MVP, MCSE 2012/Cloud, MCITP EA, MCTS Windows 2008/R2, Exchange 2007 & 2010, Exchange 2010 Enterprise Administrator, MCSE 2003/2000, MCSA Messaging 2003
   Microsoft Certified Trainer
   Microsoft MVP: Directory Services
   Active Directory, Exchange and Windows Infrastructure Engineer and Janitor
   www.delcocomputerconsulting.com