DNS resolving to multiple A records
wild...@gmail.com
wrong. :)
Our Windows 2003 FRDC (also primary DNS server) has 3 IP addresses:
172.16.1.1
192.168.3.1
10.8.0.1 (VPN)
All 3 addresses have A records pointing to the same name (SR-001)
My client workstation is on the /23 subnet (172.16.*) and it's running
Windows 7 beta.
When I perform NSLOOKUP from the Win7 client, the server returns the /
24 address first (192.168.*) followed by 172.16.1.1 and finally
10.8.0.1
This is a problem, because any attempts to connect to the server from
the client machine first try to connect to the server on 192.168.3.1,
and fail because it's the wrong subnet. After several seconds it gives
up and tries 172.16.1.1, and connects successfully.
Pinging SR-001 from the client doesn't work, because it attempts to
ping 192.168.3.1 instead of 172.16.1.1.
1. Is this a client issue or a server issue?
2. How do I make it so a NSLOOKUP resolves to the /23 address first
for clients on that subnet? (in fact, they could resolve to that
address first for all clients, that would be fine).
Help greatly appreciated!
![Meinolf Weber [MVP-DS]'s profile photo](https://lh3.googleusercontent.com/a/default-user=s40-c)
Meinolf Weber [MVP-DS]
Is that server domain controller? Domain controllers should not be multihomed(multiple
ip addresses on multiple NIC's), either RRAS server. This will create more
problems then solving them. Also security is lowered.
Can you describe more detailed your network setup and what ip/subnet is needed
for.
Best regards
Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
** Please do NOT email, only reply to Newsgroups
** HELP us help YOU!!! http://www.blakjak.demon.co.uk/mul_crss.htm
wild...@gmail.com
It has one NIC with 2 IP addresses associated to it.
172.16.1.1
192.168.3.1
All workstations are on the 172.16.* subnet.
All printers and some wireless access points are on 192.168.3.*
subnet. (Prevents client access to printer/ap config.)
10.8.0.1 is the OpenVPN adaptor on that server for VPN connection to a
second site. (We're not using RRAS - not my decision.)
Hope this helps!
Meinolf Weber [MVP-DS]
The biggest problem are the 2 ip's on the NIC. Because they are on one NIC
you have no option to disable DNS registrtation. Printers you can configure
with the security tab on the printer itself with the needed permissions to
remove access for your users.
The wireless network create via a router connection to the running network
or maybe with manageble switches and VPN's on the switch.
Also post an unedited ipconfig /all from the server and the problem client.
Best regards
Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
** Please do NOT email, only reply to Newsgroups
** HELP us help YOU!!! http://www.blakjak.demon.co.uk/mul_crss.htm
wild...@gmail.com
Sorry, made a small mistake.
172.16.1.2 is primary DC and primary DNS.
172.16.1.1 is default gateway (cisco router).
wild...@gmail.com
> Hello wilds...@gmail.com,
>
> The biggest problem are the 2 ip's on the NIC. Because they are on one NIC
> you have no option to disable DNS registrtation. Printers you can configure
> with the security tab on the printer itself with the needed permissions to
> remove access for your users.
>
> The wireless network create via a router connection to the running network
> or maybe with manageble switches and VPN's on the switch.
>
> Also post an unedited ipconfig /all from the server and the problem client.
>
> Best regards
>
> Meinolf Weber
> Disclaimer: This posting is provided "AS IS" with no warranties, and confers
> no rights.
> ** Please do NOT email, only reply to Newsgroups
> ** HELP us help YOU!!!http://www.blakjak.demon.co.uk/mul_crss.htm
DOMAIN CONTROLLER IPCONFIG /ALL:
Windows IP Configuration
Host Name . . . . . . . . . . . . : SR-001
Primary Dns Suffix . . . . . . . : DOMAIN.Internal
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : Yes
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : DOMAIN.Internal
local
Ethernet adapter openvpn TAP:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : TAP-Win32 Adapter V8
Physical Address. . . . . . . . . : 00-FF-BC-ED-B7-D1
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.8.0.1
Subnet Mask . . . . . . . . . . . : 255.255.255.252
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . : 10.8.0.2
Lease Obtained. . . . . . . . . . : 29 January 2009 21:48:30
Lease Expires . . . . . . . . . . : 29 January 2010 21:48:30
Ethernet adapter Default LAN Connection:
Connection-specific DNS Suffix . : local
Description . . . . . . . . . . . : Intel(R) PRO/1000 EB Network
Connection with I/O Acceleration
Physical Address. . . . . . . . . : 00-15-17-60-99-30
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.3.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
IP Address. . . . . . . . . . . . : 172.16.1.2
Subnet Mask . . . . . . . . . . . : 255.255.254.0
Default Gateway . . . . . . . . . : 172.16.1.1
DNS Servers . . . . . . . . . . . : 172.16.1.2
172.16.1.3
CLIENT IPCONFIG /ALL:
Windows IP Configuration
Host Name . . . . . . . . . . . . : imba
Primary Dns Suffix . . . . . . . : DOMAIN.Internal
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : DOMAIN.Internal
Wireless LAN adapter Wireless Network Connection:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek RTL8187B Wireless
802.11b/g 54Mbps USB 2.0 Network Adapter
Physical Address. . . . . . . . . : 00-16-44-D0-87-CD
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Marvell Yukon 88E8072 PCI-E
Gigabit Ethernet Controller
Physical Address. . . . . . . . . : 00-1E-68-5F-BD-12
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::b19f:aeb3:adae:4a2f%10
(Preferred)
IPv4 Address. . . . . . . . . . . : 172.16.0.12(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.254.0
Default Gateway . . . . . . . . . : 172.16.1.1
DHCPv6 IAID . . . . . . . . . . . : 218111592
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-10-CE-B5-
AE-00-1E-68-5F-BD-12
DNS Servers . . . . . . . . . . . : 172.16.1.2
172.16.1.3
NetBIOS over Tcpip. . . . . . . . : Enabled
Tunnel adapter isatap.{52BDE957-B8A9-41E8-AFA0-812F10D4F311}:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter isatap.local:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter isatap.{E17C5D39-E11F-4B36-961A-0CB2F2C56A22}:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Teredo Tunneling Pseudo-Interface:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-
Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Meinolf Weber [MVP-DS]
Hello wild...@gmail.com,
What is 172.16.1.3, configured as DNS server?
Best regards
Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
** Please do NOT email, only reply to Newsgroups
** HELP us help YOU!!! http://www.blakjak.demon.co.uk/mul_crss.htm
> 172.16.1.3
>
wild...@gmail.com
That's the second DC (also secondary DNS server).
![Ace Fekay [Microsoft Certified Trainer]'s profile photo](http://lh3.googleusercontent.com/a-/ALV-UjXqqVhI7EaT7_gXkhFKCFQ8nhaZIbo-OzClrbzK6ofJwb4uPA=s40-c)
Ace Fekay [Microsoft Certified Trainer]
wild...@gmail.com <wild...@gmail.com>, posted the following:
Hello, Wildstoo,
As Meinolf mentioned, mutltihomed DCs are not recommended and are very
problematic. It is suggested to leave a DC single homed, and put a router in
for multi-subnet connectivity. It is also recommended to use a member server
(non-DC) as a RRAS server for VPN. Of course, SBS server allows this, since
it works a little differently than the regular Windows Server versions.
Keep in mind, what you are seeing is due to one of, or both of two things:
Round Robin (where records are given in different orders), or netmask
priortizing. But I believe netmask priortizing is at play here, because one
of the cards has multiple IPs of different subnets, and the host record has
three different IPs with three different subnets. Therefore when a client on
the /23 pings or using nslookup queries for it, DNS does not know which to
respond with, and gives the response in the order you are seeing, from /24,
to /23, then /8 (descending). Normally with multiple records, DNS will try
to give the client the best response based on the querying subnet of the
client, but with multiples on one NIC, it just can't determine that and
gives you what you are seeing. On the other hand, if the querying client
does not match any subnets that exist for the host records, it gives the
response in Round Robin, which can be tested by repeatedly running nslookup
(up arrow, enter, up arrow, enter, etc), and you will see the responses
change order. But this doesn't appear to be the case in your situation.
Problematic? I would say so. How to fix it? Difficult, and this response
feature is not configurable the way you would like to see it. However, you
can disable registration of all records, and only publish one record that
your clients need using the registry. If you try to publish two of the
records, you will still see the same issue.
I am also surprised you are not seeing any AD event log errors with this
setup, either. Keep in mind, with AD Sites, the DC now becomes part of
multiple sites. Sites are used to control which GC will respond to an
authentication request (logon, printer auth, etc). This can be problematic
as well, unless the Site is configured with multiple subnets, but then again
it veers off the track of what you are trying to accomplish.
Below is a blog I put together regarding mutlihomed DCs and how to configure
one, that is if you still require the need to keep this DC multihomed.
Honestly it would be much easier and non-problematic to single home it and
use routers or VLAN capable switches to interconnect multiple subnets. Read
the sections regarding how to configure the registry to stop registration,
and only allow registration of specific records (A records and SRV netlogon
records) that need to be registered for the DC to function.
This blog can also be found at www.fekay.com/supportblogs.htm.
********************************
********************************
Multihomed DCs, DNS, RRAS servers.
By Ace Fekay, Microsoft Certified Trainer (also a Former Directory Services
MVP )
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
With all due respect, multi-homed DCs are not recommended because of the
associated issues that WILL occur with AD. If using a DC as an internet
access gateway, I recommend purchasing an inexpensive Linksys, DLink, etc,
Cable/DSL router to perform NAT for you, take out the extra NIC off the DC,
but still let the DC handle DHCP (and not the router).
If used for some other reason, I would highly recommend removing the NICs
and apps and use a non-DC for the task.
Little background on AD and DNS:
First, just to get this out of the way, if you have your ISP's DNS addresses
in your IP configuration (DCs and clients), they need to be REMOVED. If the
ISP's DNS is in there, this will cause additional problems. I usually see
errors (GPOs not working, can't find the domain, RPC issues, etc), when the
ISP's DNS servers are listed on a client, DCs and/or member servers, or with
multihomed DCs. If you have an ISP's (or some other outside DNS server or
even using your router as a DNS server) DNS addresses in your IP
configuration (all DCs, member servers and clients), they need to be REMOVED
and ONLY use the internal DNS server(s). This can be very problematic.
More background: AD uses DNS. DNS stores AD's resource and service locations
in the form of SRV records, hence how everything that is part of the domain
will find resources in the domain. If the ISP's DNS is configured in the any
of the internal AD member machines' IP properties, (including all client
machines and DCs), the machines will be asking the ISP's DNS 'where is the
domain controller for my domain?", whenever it needs to perform a function,
(such as a logon request, replication request, querying and applying GPOs,
etc). Unfortunately, the ISP's DNS does not have that info and they reply
with an "I dunno know", and things just fail. Unfortunately, the ISP's (or
your router as a DNS server) DNS doesn't have information or records about
your internal private AD domain, and they shouldn't have that sort of
information.
Also, AD registers certain records in DNS in the form of SRV records that
signify AD's resource and service locations. When there are multiple NICs,
each NIC registers. IF a client, or another DC queries DNS for this DC, it
may get the wrong record. One factor controlling this is Round Robin. If a
DC or client on another subnet that the DC is not configured on queries for
it, Round Robin will kick in offering one or the other. If the wrong one
gets offered, it may not have a route to it. On the other hand, Subnetmask
Priortization will ensure a querying client will get an IP that corresponds
to the subnet it's on, which will work. To insure everything works, stick
with one NIC.
Beause this DC is multi-homed, it requires additional configuration to
prevent the public interface addresses from being registered in DNS. This
creates a problem for internal clients locating AD to authenticate and find
other services and resources such as the Global Catalog, file sharing and
the SYSVOL DFS share and can cause GPO errors with Userenv 1000 events to be
logged, authenticating to shares and printers, logging on takes forever,
among numerous other issues.
But if you like, there are some registry changes to eliminate the
registration of the external NIC or simply use the internal networking
routing to allow access. Here's the whole list of manual steps to follow.
Another problem is the DC now becomes part of two Sites. This is another
issue that can be problematic.
But believe me, it's much easier to just get a separate NAT device or
multihome a non-DC then having to alter the DC. If the both NICs are
internal, I would suggest to pick a subnet, team the NICs and allow your
internal routers handle the traffic between subnets - Good luck!
1. Insure that all the NICS only point to your internal DNS server(s) only
and none others, such as your ISP's DNS servers' IP addresses.
2. In Network & Dialup properties, Advanced Menu item, Advanced Settings,
move the internal NIC (the network that AD is on) to the top of the binding
order (top of the list).
3. Disable the ability for the outer NIC to register. The procedure, as
mentioned, involves identifying the outer NIC's GUID number. This link will
show you how:
246804 - How to Enable-Disable Windows 2000 Dynamic DNS Registrations (per
NIC too):
http://support.microsoft.com/?id=246804
4. Disable NetBIOS on the outside NIC. That is performed by choosing to
disable NetBIOS in IP Properties, Advanced, and you will find that under the
"WINS" tab. You may want to look at step #3 in the article to show you how
to disable NetBIOS on the RRAS interfaces if this is a RRAS server.
296379 - How to Disable NetBIOS on an Incoming Remote Access Interface
[Registry Entry]:
http://support.microsoft.com/?id=296379
Note: A standard Windows service, called the "Browser service", provides the
list of machines, workgroup and domain names that you see in "My Network
Places" (or the legacy term "Network Neighborhood"). The Browser service
relies on the NetBIOS service. One major requirement of NetBIOS service is a
machine can only have one name to one IP address. It's sort of a
fingerprint. You can't have two brothers named Darrell. A multihomed machine
will cause duplicate name errors on itself because Windows sees itself with
the same name in the Browse List (My Network Places), but with different
IPs. You can only have one, hence the error generated.
5. Disable the "File and Print Service" and disable the "MS Client Service"
on the outer NIC. That is done in NIC properties by unchecking the
respective service under the general properties page. If you need these
services on the outside NIC (which is unlikely), which allow other machines
to connect to your machine for accessing resource on your machine (shared
folders, printers, etc.), then you will probably need to keep them enabled.
6. Uncheck "Register this connection" under IP properties, Advanced
settings, "DNS" tab.
7. Delete the outer NIC IP address, disable Netlogon registration, and
manually create the required records
a. In DNS under the zone name, (your DNS domain name), delete the outer
NIC's IP references for the "LdapIpAddress". If this is a GC, you will need
to delete the GC IP record as well (the "GcIpAddress"). To do that, in the
DNS console, under the zone name, you will see the _msdcs folder.
Under that, you will see the _gc folder. To the right, you will see the IP
address referencing the GC address. That is called the GcIpAddress. Delete
the IP addresses referencing the outer NIC.
i. To stop these two records from registering that information,
use the steps provided in the links below:
Private Network Interfaces on a Domain Controller Are Registered in DNS
http://support.microsoft.com/?id=295328
ii. The one section of the article that disables these records is
done with this registry entry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
(Create this Multi-String Value under it):
Registry value: DnsAvoidRegisterRecords
Data type: REG_MULTI_SZ
Values: LdapIpAddress
GcIpAddress
iii. Here is more information on these and other Netlogon Service records:
Restrict the DNS SRV resource records updated by the Netlogon service
[including GC]:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/windowsserver2003/proddocs/standard/sag_dns_pro_no_rr_in_ad.asp
b. Then you will need to manually create these two records in DNS with
the IP addresses that you need for the DC. To create the LdapIpAddress,
create a new host under the domain, but leave the "hostname" field blank,
and provide the internal IP of the DC, which results in a record that looks
like:
(same as parent) A 192.168.5.200 (192.168.5.200 is used for illustrative
purposes)
i. You need to also manually create the GcIpAddress as well, if
this is a GC. That would be under the _msdcs._gc SRV record under the zone.
It is created in the same fashion as the LdapIpAddress mentioned above.
8. In the DNS console, right click the server name, choose properties, then
under the "Interfaces" tab, force it only to listen to the internal NIC's IP
address, and not the IP address of the outer NIC.
9. Since this is also a DNS server, the IPs from all NICs will register,
even if you tell it not to in the NIC properties. See this to show you how
to stop that behavior (this procedure is for Windows 2000, but will also
work for Windows 2003):
275554 - The Host's A Record Is Registered in DNS After You Choose Not to
Register the Connection's Address:
http://support.microsoft.com/?id=275554
10. If you haven't done so, configure a forwarder. You can use 4.2.2.2 if
not sure which DNS to forward to until you've got the DNS address of your
ISP.
How to set a forwarder? Good question. Depending on your operating
system,choose one of the following articles:
300202 - HOW TO: Configure DNS for Internet Access in Windows 2000
http://support.microsoft.com/?id=300202&FR=1
323380 - HOW TO: Configure DNS for Internet Access in Windows Server 2003
(How to configure a forwarder):
http://support.microsoft.com/d/id?=323380
Active Directory communication fails on multihomed domain controllers
http://support.microsoft.com/kb/272294
<==*** Some additional reading ***==>
More links to read up and understand what is going on:
292822 - Name Resolution and Connectivity Issues on Windows 2000 Domain
Controller with Routing and Remote Access and DNS Insta {DNS and RRAS and
unwanted IPs registering]:
http://support.microsoft.com/?id=292822
Active Directory communication fails on multihomed domain controllers
http://support.microsoft.com/kb/272294
246804 - How to enable or disable DNS updates in Windows 2000 and in Windows
Server 2003
http://support.microsoft.com/?id=246804
295328 - Private Network Interfaces on a Domain Controller Are Registered in
DNS [also shows DnsAvoidRegisterRecords LdapIpAddress to avoid reg
sameasparent private IP]:
http://support.microsoft.com/?id=295328
306602 - How to Optimize the Location of a DC or GC That Resides Outside of
a Client's Site [Includes info LdapIpAddress and GcIpAddress information and
the SRV mnemonic values]:
http://support.microsoft.com/?id=306602
825036 - Best practices for DNS client settings in Windows 2000 Server and
in Windows Server 2003 (including how-to configure a forwarder):
http://support.microsoft.com/default.aspx?scid=kb;en-us;825036
291382 - Frequently asked questions about Windows 2000 DNS and Windows
Server 2003 DNS
http://support.microsoft.com/?id=291382
296379 - How to Disable NetBIOS on an Incoming Remote Access Interface
[Registry Entry]:
http://support.microsoft.com/?id=296379
Rid Pool Errors and other mutlhomed DC errors, and how to configure a
multihomed DC, Ace Fekay, 24
Feb 2006
http://www.ureader.com/message/3244572.aspx
_________________________
+++++++++++++++++++++++++++++++++++++++++++++++++++++++