Q198408: Microsoft DNS Server Registry Parameters, Part 1 of 3
Article: Q198408
Product(s): Microsoft Windows NT
Version(s): winnt:4.0
Operating System(s):
Keyword(s):
Last Modified: 10-AUG-2001
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The information in this article applies to:
- Microsoft Windows NT Server version 4.0
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IMPORTANT: This article contains information about editing the registry.
Before you edit the registry, make sure you understand how to restore it if
a problem occurs. For information about how to do this, view the "Restoring
the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key"
Help topic in Regedt32.exe.
SUMMARY
=======
This article consists of 3 parts and describes settings for the Microsoft Domain
Name Service (DNS) SERVER. You can modify most settings using the DNSADMIN tool,
although some settings can only be altered using Registry Editor.
For additional information, please see the following articles in the Microsoft
Knowledge Base:
Q198409 Microsoft DNS Server Registry Parameters, Part 2 of 3
Q198410 Microsoft DNS Server Registry Parameters, Part 3 of 3
MORE INFORMATION
================
WARNING: Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee that
problems resulting from the incorrect use of Registry Editor can be solved. Use
Registry Editor at your own risk.
For information about how to edit the registry, view the "Changing Keys And
Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete
Information in the Registry" and "Edit Registry Data" Help topics in
Regedt32.exe. Note that you should back up the registry before you edit it.
To change these parameters, use the following procedure:
1. Start Registry Editor (Regedt32.exe).
2. From the HKEY_LOCAL_MACHINE subtree, go to the following key:
\SYSTEM\CurrentControlSet\Services
3. From the Edit menu, click Add Value and add a value to the key described in
the appropriate entry below. Type in the value, and use the "Data Type" check
box to set the value type.
4. Click OK.
5. Quit Registry Editor.
6. Restart the DNS Server for the above changes to take affect.
All of the DNS parameters are registry values located under subkeys of:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\parameters
Server Parameters
-----------------
Several registry parameters determine behavior of the entire server. Each of
these is a registry value under
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DNS\Parameters
NOTE: These registry keys are read only at startup. Some may be reset and, in
some cases, the server behavior dynamically changed, through the DNS
Administrator. But if manually reset the DNS server MUST be restarted to pick up
the new value.
BootMethod
----------
Value: BootMethod
Added: SP4 (April 98)
Type: DWORD
Defaul NoKey
Functio Determine boot method.
This key determines the source of the DNS boot information server configuration,
and list and configuration of authoritative zones. This key makes the
EnableBootMethod key (see below) obsolete.
NOTE: If the EnableRegistryBoot key is read, the DNS server will read its value
to determine the proper value of the BootMethod key; no administrator
intervention is required. The EnableRegistryBoot key is kept around for backward
compatibility.
There are three possible sources of boot information and three possible
BootMethod values:
#define BOOT_METHOD_UNINITIALIZED (0)
#define BOOT_METHOD_FILE (1)
#define BOOT_METHOD_REGISTRY (2)
- When starting from a file, the DNS server attempts to locate a traditional
BIND-style boot file. The file must be in the System32\Dns folder and be
named <boot>. Note that, when starting from a boot file, the DNS server
will still read server registry parameters that have no boot file analog.
However, some server registry parameters may be configured in standard boot
files:
- Forwarders
- Slave
- NoRecursion
For these, any existing registry entry will be deleted, whether or not they
are specified in the boot file.
NOTE: New versions of BIND have a new boot file style to attempt to provide a
similar level of detailed control available in the Windows NT DNS server.
This new style is NOT supported. Users should simply configure the DNS server
through the DNS Manager and use registry or directory boot.
- For a registry boot, all the server and zone configuration information is
read from the registry. It is located in:
\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS.
Starting with Windows NT 4.0 SP4, the DNS server is able to write back a boot
file. Thus, administrator updates that alter boot file information cause a new
boot file to be written back. Furthermore, when starting from the boot file, the
server will still check existing registry zone information for values (for
example, notify lists, secure secondaries) that can not be specified in a boot
file.
EnableRegistryBoot
------------------
Value: EnableRegistryBoot
Added Windows NT 4.0
Type: DWORD (Boolean)
Defaul NoKey
Function: Determine boot method.
Use of this key is only for pre-Service Pack 4 versions of Dns.exe; see above key
"BootMethod" for explanation.
If the key does not exist or is 0, the server attempts to find a "boot" file in
the DNS directory and use it to determine server configuration and authoritative
zones. If the boot file is NOT found, the server will start up with no
authoritative zones as a caching-only server (a message is logged to this
effect).
If the key is nonzero, DNS starts using only registry information, and the boot
file, if any, is ignored.
RpcProtocol
-----------
Value: RpcProtocol
Added: Windows NT 4.0
Type: DWORD
Default: 0xffffffff (Use all protocols)
Function: Determine which protocols administrative RPC runs over
If the key is nonzero, the key value is matched bit-wise against available RPC
protocols:
TCP/IP -- 0x1
NamedPipes -- 0x2
LPC -- 0x4
For those protocols contained in the key, the DNS server sets up RPC endpoints to
allow connections over those protocols from the admin tool.
Disabling RPC:
If a computer is on the Internet, it is often desirable to disable RPC. If this
is being done for the entire computer, the DependOnService DNS server key (this
is under DNS key, not under DNS\Parameters) should be edited to remove the last
two entries, RpcSS and NtLmSsp. This eliminates the dependency of the DNS server
on RPC and the standard Windows NT network security information, allowing it to
boot without those services.
Starting with Windows NT 4.0 SP4, the code is more responsive to a desire to turn
RPC off. Setting the RpcProtocol key to zero will suffice.
EventLogLevel
-------------
Value: EventLogLevel
Added: SP4 (April 98)
Type: DWORD
Default: NoKey (Log all events)
Function: Determines level of logging to event log.
The DNS server can generate quite a few events of both a serious and a routine
nature. This key allows the administrator to limit the logging to the level
preferred.
The value of the key is the value of the LEAST serious event the DNS server will
log, with the event types taken directly from the Win32 SDK:
#define EVENTLOG_ERROR_TYPE 0x0001
#define EVENTLOG_WARNING_TYPE 0x0002
#define EVENTLOG_INFORMATION_TYPE 0x0004
Examples: By default, a nonexistent EventLogLevel key has the value 4, and all
events are logged. To log only warning and error events, set the registry key to
2. To log only errors, set the registry key to 1. To disable event logging
completely, set the registry key to 0.
LogLevel
--------
Value: LogLevel
Added: SP4 (April 98)
Type: DWORD (Bitfield)
Default: NoKey (Zero -- No logging)
Function: Determines level of logging to file (Dns.log).
The DNS server can generate a more detailed log than is practical to include in
the Windows NT event log. This includes everything from simply including events
excluded from the event log, to a summary of every packet in and out of the
server.
The registry key is a DWORD bit field indicating the various portions of logging
to enable:
#define DNS_LOG_LEVEL_ALL_PACKETS 0x0000ffff
#define DNS_LOG_LEVEL_NON_QUERY 0x000000fe
#define DNS_LOG_LEVEL_QUERY 0x00000001
#define DNS_LOG_LEVEL_NOTIFY 0x00000010
#define DNS_LOG_LEVEL_UPDATE 0x00000020
#define DNS_LOG_LEVEL_QUESTIONS 0x00000100
#define DNS_LOG_LEVEL_ANSWERS 0x00000200
#define DNS_LOG_LEVEL_SEND 0x00001000
#define DNS_LOG_LEVEL_RECV 0x00002000
#define DNS_LOG_LEVEL_UDP 0x00004000
#define DNS_LOG_LEVEL_TCP 0x00008000
#define DNS_LOG_LEVEL_DS_WRITE 0x00010000
#define DNS_LOG_LEVEL_DS_UPDATE 0x00020000
#define DNS_LOG_LEVEL_FULL_PACKETS 0x01000000
#define DNS_LOG_LEVEL_WRITE_THROUGH 0x80000000
NoRecursion
-----------
Value: NoRecursion
Added: Windows NT 4.0
Type: DWORD (Boolean)
Default: NoKey (Do recursion)
Function: Determine whether or not server does recursive lookups.
DNS server can answer queries for names outside of their authoritative zones in
two ways:
- Referral: Respond to query with the list (NS and A records) of "closest"
servers to the queried name that it knows.
- Recursion: Send query on to the "closest" DNS server to the queried name that
it knows, and continue process (if necessary) until it gets a response back
for the original query. Then send the response back to the client. A bit in
the header of the DNS packet indicates the method preferred by the client.
If the NoRecusion key does not exist or is zero, the DNS server uses whichever
method is requested in the packet.
If the NoRecursion key is nonzero, the DNS server always uses referral regardless
of the client request. NoRecursion would generally be used when clients are
being limited to resolving names on a given server (for example, names on an
intranet), or when the server is incapable of resolving external names and the
clients are expected to fall over to another DNS server for resolution of
external (Internet) names.
Forwarders
----------
Value: Forwarders
Added: Windows NT 4.0
Type: BINARY
Default: NoKey (No forwarders)
Function: Determines forwarders server list.
DNS servers may be configured to send all their recursive queries to a selected
list of servers. Queries to these forwarders are done recursively (as a normal
client query), rather than iteratively. The forwarder contacts the remote server
or servers until it gets the response and responds to the DNS server with the
complete query response, suitable for sending back to the client. During this
process, the DNS server using forwarders essentially behaves as a DNS client to
the forwarding server.
This behavior is often desirable when access to remote DNS servers (on the
Internet) requires use of a slow or more expensive link. Using forwarders can
cut down on expensive traffic in two ways.
- Cutting traffic across slow links.
Example: Your DNS has a slow expensive dial-up connection to an ISP. When the
DNS receives a query for a remote name, it can directly contact remote
servers on the Internet until it can determine the authoritative server for
the name, contact it, and get a response. This may involve several queries
across the slow link. It is better to specify (if allowed) the ISP's DNS
server on the Internet as a forwarder. The query is forwarded to this server
and it does all the remote queries and responds only when it has the complete
answer. This is a single round trip across the slow link.
- Sharing remote results.
Example: Your organization has several DNS servers on a LAN. Rather than have
each server try and send queries through a firewall and out to the Internet,
all the DNS servers are configured to forward queries to one DNS server
(perhaps sitting on the firewall), which makes the necessary queries to the
remote servers. In the process, this forwarding server will build up a rich
cache from the responses it receives. And, when a local DNS server forwards a
query to it, there is a reasonable chance that it already has the answer (or
a head start on getting to the answer) from a previous query it answered for
another DNS server. Thus, the total amount of remote traffic is reduced.
The forwarders list is a list of IP addresses of servers to forward to. One
server should be preferred (to preferentially build up its cache), but more than
one should generally be given. Retries are indicated by repeating entries.
The Forwarders key is a list of IP addresses for the DNS server to forward to.
The list is not dotted IP strings, but a counted array of raw addresses in net
byte order. It should be configured through the Server Properties, Forwarders
dialog box in the Administrator tool. Editing the registry key is discouraged.
If the Forwarders key exists, the DNS server forwards to servers in the list. If
the Forwarders key does not exist, the DNS server uses the normal iterative
query process to answer recursive queries for remote names.
IsSlave
-------
Value: IsSlave
Added: Windows NT 4.0
Type: DWORD (Boolean)
Default: NoKey (Not a slave)
Function: Determine if slave server.
When a DNS server is using Slave (and Forwarders -- see Forwarders key
description), it can stop and fail the query when it does not get a response
from any of the forwarders servers /Vs Forwarders: configuration where the DNS
server can attempt to resolve the query itself using normal iterative queries.
The key is NOT read if Forwarders are not configured. If the IsSlave key does
not exist or is zero, the DNS falls back to normal recursive query resolution
when forwarders fail to respond.
If the IsSlave key is nonzero, the server fails (answers the original query with
SERVER_FAILURE) when the forwarders do not respond.
Do NOT change this key. Use the Forwarders dialog box in the DNS Administrator
tool to set forwarding properties. If this key is deleted while forwarders are
configured, the server may fail to start or fail to resolve remote names
properly.
ForwardingTimeout
-----------------
Value: ForwardingTimeout
Added: Windows NT 4.0
Type: DWORD
Default: NoKey
Function: Set forwarding timeout.
When using forwarders, queries are sent to each forwarder in the list, which is
given a timeout within which to respond before the next forwarder is tried. The
ForwardingTimeout key is read ONLY when forwarders are configured. Its value
determines the forwarding timeout in seconds.
Do NOT adjust this key. Use the Forwarders dialog box in the DNS Administrator
tool to set forwarding properties. If this key is deleted while forwarders are
configured, the server may fail to start or fail to resolve remote names
properly.
ForwardDelegations
------------------
Value: ForwardDelegations
Added: SP4 (April 1998)
Type: DWORD (Boolean)
Default: NoKey (Do NOT forward delegations.)
Function: Determine whether queries to delegated sub-zones are
forwarded.
Queries to delegations are sent directly, not forwarded.
Example:
A server hosts samples.microsoft.com and it is set up to forward across a
firewall to ns.isp.com. Another server has a delegation for
finance.samples.microsoft.com to ns.finance.samples.microsoft.com, a computer
inside the firewall. If the second server receives a query for
golf-schedule.finance.samples.microsoft.com, the desired behavior is NOT to send
the query out to the forwarder. Rather it should send it directly to
ns.finance.samples.microsoft.com.
The ForwardDelegations value allows you to revert to previous forward everything
behavior. This would only be desired when the delegation itself was at a remote
site that was reachable through the forwarder.
MaxCacheTtl
-----------
Value: MaxCacheTtl
Added: SP4 (April 1998)
Type: DWORD
Default: NoKey (Cache for up to one day)
Function: Set maximum caching TTL.
Records from recursive queries are cached by the DNS server. The length of time
they remain in the cache is determined by the TimeToLive (TTL) field in the
record. This field is a DWORD giving the caching time in seconds; therefore, the
TTL can be quite long. Limiting the caching time can help limit the memory used
by the cache and make sure that stale data does not accumulate in the cache.
Additional query words: flags
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Keywords :
Technology : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version : winnt:4.0
Issue type : kbinfo
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