Re: the effects on running dcpromo to fix anAD issue.
- From: Meinolf Weber [MVP-DS]
- Date: Mon, 3 Aug 2009 14:58:09 +0000 (UTC)
Hello Fred,
This belongs to the multihomed server. I assume in the DNS zones you will see both ip addresses registered.
See:
"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."
This is from Ace Fekay's complete article:
Multihomed DCs, DNS, RRAS servers.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
Below are the manual steps in more detail, which I had outlined in the above paragraph:
Honestly, multi-homed DCs are not recommended because of the associated issues that can occur, as you've encountered. We usually 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).
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.
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.
Since 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. Here's the whole list of manual steps to follow.
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. - 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 DNShttp://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
+++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++
--
Regards,
Ace
This posting is provided "AS-IS" with no warranties or guarantees and confers no rights.
Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft MVP - Directory Services
Microsoft Certified Trainer
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
OK, i'm gathering that info now, but i have just stumbled on
something.
when server A pings server B, it's resolving the RAS adapter's IP
address
not the server's IP.
Does that help?
"Meinolf Weber [MVP-DS]" <meiweb(nospam)@gmx.de> wrote in message
news:ff16fb662bda18cbe2613944e8cd@xxxxxxxxxxxxxxxxxxxxxxx
Hello Fred,
Do you run any firewall on the servers? They can block ICMP protocol.
So again, a complete unedited ipconfig /all, dcdiag /v, netdiag and
repadmin /showrepl can help us really.
If you are scared about domain names and ip addresses, just use
domain.com for example or domain to keep the format you have. Also
for server names, change them but with the same format.
The ip address range 10.x.x.x, 172.x.x.x and 192.168.x.x are prviate
ip range so it is NOT possible to access them over the internet.
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
Thanks for the advice so far Guys, I do hear what your saying and
completely agree with the thoughts on mixing roles on one server,
but in the circumstances, this has happened historicaly here, and at
this point in time, i just need to get things working again. At this
time i cannot afford the time or budget to add additional hardware
to fix this issue, however i will carry out a migration in the near
future.
We have guys all over the world who are relying on vpn connectivity,
to enable them to work, so i am very limited as to what i can do
with the RRAS side of things.
One thing which may be of assistance is that replication appears to
be working one way, i.e from A to B, but not B to A ( B will be the
exchange DC ).
One other thing for the melting pot. Why is it that i can ping
either server from a workstation and get a reply, but when i ping
from A to B servers the ping times out? pinging from B to A will
reply!
Thanks
"Meinolf Weber [MVP-DS]" <meiweb(nospam)@gmx.de> wrote in message
news:ff16fb662bc518cbe1a1df8662b1@xxxxxxxxxxxxxxxxxxxxxxx
Hello Fred,
As Ace already stated RRAS on DC is not a good idea, also Exchange.
So if you don't need RRAS services uninstall it and if you need it
use a dedicated member server for it.
Also post an unedited repadmin /showrepl to check what is going on
with your replication after changing the RRAS option.
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
Hi guys, thanks for your help so far,
what is happening is this,
we have two dc's in two different offices. both run on the same
domain. I
first spotted that DFS was not replicating correctly, and
documents
in
site
A were not propagating to site B.
Also I created some new AD user accounts, and these did / do not
find
their
way overto site b either. If i create anything in site B however
that
does
find it's way across to site A's DC.
now the really curious part. if i ping from site A's dc to site
b's
dc
it
times out. however back the other way it replies. if i type in
\\serverb\c$
on site a's server it see's what is stored on site b's server and
vice
versa
with B to A. in short replication of data and ad is only going one
way
and
not both ways.
Site A's DC also runs exchange, so i'm treating that with kids
gloves.
Exchange is running fine btw.
re server version, we have the 64 bit version, not sure if this
effects getting 2003 server support tools or not.
re ipconfig /all here goes
server B
host name serverB
pri dns suffix xxxx.local
node type unknown
ip routing enabled yes
wins proxy yes
dns suffix search xxxx.local
ethernet adapter
dhcp enabled no
ip address 192.168.168.3
sub 255.255.255.0
dfg 192.168.168.5
dns 192.168.168.3
10.3.20.3 (server A)
server A
host name serverA
pri dns suffix xxxx.local
node type unknown
ip routing enabled yes
wins proxy yes
dns suffix search xxxx.local
ipaddress 192.168.1.5 not sure why this is present,
but
the ip
does show up in the nic's ip properties & replies to a ping
sub 255.255.255.0
ip address 10.3.20.3
sub 255.255.255.0
dfg 10.3.20.5
dns 10.3.20.3
192.168.168.3
tia
"Ace Fekay [MCT]" <aceman@xxxxxxxxxxxxxxxxxxxxxxx> wrote in
message
news:%23yVGku%23DKHA.1252@xxxxxxxxxxxxxxxxxxxxxxx
"Fred Bloggs" <Fred@xxxxxxxxxxx> wrote in message
news:6C8B8EBE-3DDB-4A9D-833F-626D3A103DBF@xxxxxxxxxxxxxxxx
Hi, I'm having a huge issue with 2 servers on the same networkHi Fred,
talking to eachother, and i'm beginning to think that one server
in particular is not very happy with itself as such.
I have been advised to run dcpromo to remove the server (2003
DC) from the network, and then run dcpromo again to bring it
back in again. There is another 2003 DC on the same domain, so
it's not the last server on the domain.
My question is though, there is data currently on the server
which is unhappy, what will happen to the shares and permisions
etc on this server if i dcpromo it? Will it lose all AD info or
will it be retained when i reintroduce the server?
Thanks
In addition to the diagnostics requested by Paul and Meinolf, can
you post an ipconfig /all from both DCs so we can rule out basic
configuration issues that could have caused the problem? I'm not
sure what happened to the DC(s), and you haven't provided any
specifics, but this can *possibly* be resolved without going
through a demotion/promotion. You never know, it could be an easy
fix.
-- Ace
This posting is provided "AS-IS" with no warranties or guarantees
and confers no rights.
Please reply back to the newsgroup or forum to benefit from
collaboration among responding engineers, and to help others
benefit from your resolution.
Ace Fekay, MCT, MCTS Exchange, MCSE, MCSA 2003 & 2000, MCSA
Messaging
Microsoft Certified Trainer
aceman@xxxxxxxxxxxxxxxxxxxxxxx
http://twitter.com/acefekay
For urgent issues, you may want to contact Microsoft PSS
directly.
Please check http://support.microsoft.com for regional support
phone
numbers.
.
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