Frequently asked questions about Windows 2000 DNS and Windows Server 2003
DNS
SUMMARY
This article describes DNS functionality in Windows 2000 and Windows Server 2003, and
provides answers to frequently asked questions about Windows 2000 and Windows Server
2003 DNS.
MORE INFORMATION
DNS is the backbone of Active Directory and the primary name resolution mechanism of
Windows 2000 and Windows Server 2003. Windows 2000 and Windows Server 2003 domain
controllers dynamically register information about themselves and about Active Directory in
DNS. Other Windows 2000 and Windows Server 2003 domain controllers, servers, and
workstations that are part of the domain query DNS to find Active Directory-related
information. If DNS is not set up correctly, domain-wide issues can occur such as replication
between domain controllers. You may also be unable to log on to the domain or to join the
domain from a workstation or server.
Question: What are the common mistakes that are made when administrators set up DNS on
network that contains a single Windows 2000 or Windows Server 2003 domain controller?
Answer: The most common mistakes are:
• The domain controller is not pointing to itself for DNS resolution on all network interfaces.
• The "." zone exists under forward lookup zones in DNS.
• Other computers on the local area network (LAN) do not point to the Windows 2000 or
Windows Server 2003 DNS server for DNS.
Question: Why do I have to point my domain controller to itself for DNS?
Answer: The Netlogon service on the domain controller registers a number of records in DNS
that enable other domain controllers and computers to find Active Directory-related
information. If the domain controller is pointing to the Internet service provider's (ISP) DNS
server, Netlogon does not register the correct records for Active Directory, and errors are
generated in Event Viewer. In Windows Server 2003, the recommended DNS configuration is to
configure the DNS client settings on all DNS servers to use themselves as their own primary
DNS server, and to use a different domain controller in the same domain as their alternative
DNS server, preferably another domain controller in the same site. This process also works
around the DNS "Island" problem in Windows 2000. You must always configure the DNS client
settings on each domain controller's network interface to use the alternative DNS server
addresses in addition to the primary DNS server address.
For more information about the Windows 2000 DNS "Island" problem, see "Chapter 2 -
Structural Planning for Branch Office Environments" in the "Planning" section of the Windows
2000 Server Active Directory Branch Office Planning Guide at the following Microsoft Web site:
http://www.microsoft.com/windows2000/techinfo/planning/activedirectory/branchoffice/default
.asp
Question: What does a domain controller register in DNS?
Answer: The Netlogon service registers all the SRV records for that domain controller. These
records are displayed as the _msdcs, _sites, _tcp, and _udp folders in the forward lookup zone
that matches your domain name. Other computers look for these records to find Active
Directory-related information.
Question: Why can't I use WINS for name resolution like it is used in Microsoft Windows NT
4.0?
Answer: A Windows 2000 or Windows Server 2003 domain controller does not register Active
Directory-related information with a WINS server; it only registers this information with a DNS
server that supports dynamic updates such as a Windows 2000 or Windows Server 2003 DNS
server. Other Windows 2000-based and Windows Server 2003-based computers do not query
WINS to find Active Directory-related information.
Question: If I remove the ISP's DNS server settings from the domain controller, how does it
resolve names such as Microsoft.com on the Internet?
Answer: As long as the "." zone does not exist under forward lookup zones in DNS, the DNS
service uses the root hint servers. The root hint servers are well-known servers on the Internet
that help all DNS servers resolve name queries.
Question: What is the "." zone in my forward lookup zone?
Answer: This setting designates the Windows 2000 or Windows Server 2003 DNS server to be
a root hint server and is usually deleted. If you do not delete this setting, you may not be able
to perform external name resolution to the root hint servers on the Internet.
For more information, click the following article number to view the article in the Microsoft
Knowledge Base:
229840 DNS server's root hints and forwarder pages are unavailable
Question: Do I need to configure forwarders in DNS?
Answer: No. By default, Windows 2000 DNS uses the root hint servers on the Internet;
however, you can configure forwarders to send DNS queries directly to your ISP's DNS server
or other DNS servers. Most of the time, when you configure forwarders, DNS performance and
efficiency increases, but this configuration can also introduce a point of failure if the forwarding
DNS server is experiencing problems. The root hint server can provide a level of redundancy in
exchange for slightly increased DNS traffic on your Internet connection. Windows Server 2003
DNS will query root hints servers if it cannot query the forwarders.
Question: Should I point the other Windows 2000-based and Windows Server 2003-based
computers on my LAN to my ISP's DNS servers?
Answer: No. If a Windows 2000-based or Windows Server 2003-based server or workstation
does not find the domain controller in DNS, you may experience issues joining the domain or
logging on to the domain. A Windows 2000-based or Windows Server 2003-based computer's
preferred DNS setting should point to the Windows 2000 or Windows Server 2003 domain
controller running DNS. If you are using DHCP, make sure that you view scope option #15 for
the correct DNS server settings for your LAN.
Question: Do I need to point computers that are running Windows NT 4.0 or Microsoft
Windows 95, Microsoft Windows 98, or Microsoft Windows 98 Second Edition to the Windows
2000 or Windows Server 2003 DNS server?
Answer: Legacy operating systems continue to use NetBIOS for name resolution to find a
domain controller; however it is recommended that you point all computers to the Windows
2000 or Windows Server 2003 DNS server for name resolution.
Question: What if my Windows 2000 or Windows Server 2003 DNS server is behind a proxy
server or firewall?
Answer: If you are able to query the ISP's DNS servers from behind the proxy server or
firewall, Windows 2000 and Windows Server 2003 DNS server is able to query the root hint
servers. UDP and TCP Port 53 should be open on the proxy server or firewall.
Question: What should I do if the domain controller points to itself for DNS, but the SRV
records still do not appear in the zone?
Answer: Check for a disjointed namespace, and then run Netdiag.exe /fix. You must install
Support Tools from the Windows 2000 Server or Windows Server 2003 CD-ROM to run
Netdiag.exe.
For more information about how to check for a disjointed namespace, click the following article
number to view the article in the Microsoft Knowledge Base:
257623 The DNS suffix of the computer name of a new domain controller may not match the
name of the domain after you install upgrade a Windows NT 4.0 Primary domain controller to
Windows 2000
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.
DNS
SUMMARY
This article describes DNS functionality in Windows 2000 and Windows Server 2003, and
provides answers to frequently asked questions about Windows 2000 and Windows Server
2003 DNS.
MORE INFORMATION
DNS is the backbone of Active Directory and the primary name resolution mechanism of
Windows 2000 and Windows Server 2003. Windows 2000 and Windows Server 2003 domain
controllers dynamically register information about themselves and about Active Directory in
DNS. Other Windows 2000 and Windows Server 2003 domain controllers, servers, and
workstations that are part of the domain query DNS to find Active Directory-related
information. If DNS is not set up correctly, domain-wide issues can occur such as replication
between domain controllers. You may also be unable to log on to the domain or to join the
domain from a workstation or server.
Question: What are the common mistakes that are made when administrators set up DNS on
network that contains a single Windows 2000 or Windows Server 2003 domain controller?
Answer: The most common mistakes are:
• The domain controller is not pointing to itself for DNS resolution on all network interfaces.
• The "." zone exists under forward lookup zones in DNS.
• Other computers on the local area network (LAN) do not point to the Windows 2000 or
Windows Server 2003 DNS server for DNS.
Question: Why do I have to point my domain controller to itself for DNS?
Answer: The Netlogon service on the domain controller registers a number of records in DNS
that enable other domain controllers and computers to find Active Directory-related
information. If the domain controller is pointing to the Internet service provider's (ISP) DNS
server, Netlogon does not register the correct records for Active Directory, and errors are
generated in Event Viewer. In Windows Server 2003, the recommended DNS configuration is to
configure the DNS client settings on all DNS servers to use themselves as their own primary
DNS server, and to use a different domain controller in the same domain as their alternative
DNS server, preferably another domain controller in the same site. This process also works
around the DNS "Island" problem in Windows 2000. You must always configure the DNS client
settings on each domain controller's network interface to use the alternative DNS server
addresses in addition to the primary DNS server address.
For more information about the Windows 2000 DNS "Island" problem, see "Chapter 2 -
Structural Planning for Branch Office Environments" in the "Planning" section of the Windows
2000 Server Active Directory Branch Office Planning Guide at the following Microsoft Web site:
http://www.microsoft.com/windows2000/techinfo/planning/activedirectory/branchoffice/default
.asp
Question: What does a domain controller register in DNS?
Answer: The Netlogon service registers all the SRV records for that domain controller. These
records are displayed as the _msdcs, _sites, _tcp, and _udp folders in the forward lookup zone
that matches your domain name. Other computers look for these records to find Active
Directory-related information.
Question: Why can't I use WINS for name resolution like it is used in Microsoft Windows NT
4.0?
Answer: A Windows 2000 or Windows Server 2003 domain controller does not register Active
Directory-related information with a WINS server; it only registers this information with a DNS
server that supports dynamic updates such as a Windows 2000 or Windows Server 2003 DNS
server. Other Windows 2000-based and Windows Server 2003-based computers do not query
WINS to find Active Directory-related information.
Question: If I remove the ISP's DNS server settings from the domain controller, how does it
resolve names such as Microsoft.com on the Internet?
Answer: As long as the "." zone does not exist under forward lookup zones in DNS, the DNS
service uses the root hint servers. The root hint servers are well-known servers on the Internet
that help all DNS servers resolve name queries.
Question: What is the "." zone in my forward lookup zone?
Answer: This setting designates the Windows 2000 or Windows Server 2003 DNS server to be
a root hint server and is usually deleted. If you do not delete this setting, you may not be able
to perform external name resolution to the root hint servers on the Internet.
For more information, click the following article number to view the article in the Microsoft
Knowledge Base:
229840 DNS server's root hints and forwarder pages are unavailable
Question: Do I need to configure forwarders in DNS?
Answer: No. By default, Windows 2000 DNS uses the root hint servers on the Internet;
however, you can configure forwarders to send DNS queries directly to your ISP's DNS server
or other DNS servers. Most of the time, when you configure forwarders, DNS performance and
efficiency increases, but this configuration can also introduce a point of failure if the forwarding
DNS server is experiencing problems. The root hint server can provide a level of redundancy in
exchange for slightly increased DNS traffic on your Internet connection. Windows Server 2003
DNS will query root hints servers if it cannot query the forwarders.
Question: Should I point the other Windows 2000-based and Windows Server 2003-based
computers on my LAN to my ISP's DNS servers?
Answer: No. If a Windows 2000-based or Windows Server 2003-based server or workstation
does not find the domain controller in DNS, you may experience issues joining the domain or
logging on to the domain. A Windows 2000-based or Windows Server 2003-based computer's
preferred DNS setting should point to the Windows 2000 or Windows Server 2003 domain
controller running DNS. If you are using DHCP, make sure that you view scope option #15 for
the correct DNS server settings for your LAN.
Question: Do I need to point computers that are running Windows NT 4.0 or Microsoft
Windows 95, Microsoft Windows 98, or Microsoft Windows 98 Second Edition to the Windows
2000 or Windows Server 2003 DNS server?
Answer: Legacy operating systems continue to use NetBIOS for name resolution to find a
domain controller; however it is recommended that you point all computers to the Windows
2000 or Windows Server 2003 DNS server for name resolution.
Question: What if my Windows 2000 or Windows Server 2003 DNS server is behind a proxy
server or firewall?
Answer: If you are able to query the ISP's DNS servers from behind the proxy server or
firewall, Windows 2000 and Windows Server 2003 DNS server is able to query the root hint
servers. UDP and TCP Port 53 should be open on the proxy server or firewall.
Question: What should I do if the domain controller points to itself for DNS, but the SRV
records still do not appear in the zone?
Answer: Check for a disjointed namespace, and then run Netdiag.exe /fix. You must install
Support Tools from the Windows 2000 Server or Windows Server 2003 CD-ROM to run
Netdiag.exe.
For more information about how to check for a disjointed namespace, click the following article
number to view the article in the Microsoft Knowledge Base:
257623 The DNS suffix of the computer name of a new domain controller may not match the
name of the domain after you install upgrade a Windows NT 4.0 Primary domain controller to
Windows 2000
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.
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