MORE INFORMATION
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
To change these parameters, follow these steps:
- Click Start, click Run, and then type regedit in the Open box.
- Locate the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- Click Add Value on the Edit menu, type the value the value that you want, and then set the value type under Data Type.
- Click OK.
- Quit Registry Editor.
- Restart the computer to make the change take effect.
all the TCP/IP parameters are registry values that are located under one of two different subkeys of
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
Tcpip\Parameters
Tcpip\Parameters\Interfaces\ID for Adapter
is the network adapter that TCP/IP is bound to. To determine the relationship between an Adapter ID and a network connection, view
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\<ID for Adapter>\Connection. The
Name value in these keys provides the friendly name for a network connection that is used in the Network Connections folder. Values under these keys are specific to each adapter. Parameters that have a DHCP configured value and a statically configured value may or may not exist. Their existence depends on whether the computer or the adapter is DHCP configured and whether static override values are specified. You must restart the computer for a change to take effect.
Standard parameters that you can configure by using Registry Editor
The following parameters are installed with default values by the Network tool in Control Panel during the installation of the TCP/IP components. You can use Registry Editor to modify them.
DatabasePath
Key: Tcpip\Parameters
Value Type: REG_EXPAND_SZ - Character string
Valid Range: A valid Windows NT file path
Default: %SystemRoot%\System32\Drivers\Etc
Description: This parameter specifies the
path of the standard Internet database files
(HOSTS, LMHOSTS, NETWORKS, PROTOCOLS). It is
used by the Windows Sockets interface.
ForwardBroadcasts
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: Forwarding of broadcasts is not
supported. This parameter is ignored.
UseZeroBroadcast
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: If this parameter is set to 1
(True), the IP will use zeros-broadcasts
(0.0.0.0) instead of ones-broadcasts
(255.255.255.255). Most computers use ones-broadcasts, but some computers that are derived from BSD
implementations use zeros-broadcasts. Computers
that use different broadcasts do not
interoperate well on the same network.
Optional parameters that you can configure by using Registry Editor
Generally, these parameters do not exist in the registry. You can create them
to modify the default behavior of the TCP/IP protocol driver.
ArpAlwaysSourceRoute
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False or True)
Default: 0 (False)
Description: If you set this parameter to 1,
TCP/IP transmits ARP queries with
source routing enabled on Token Ring
networks. By default, the stack transmits ARP
queries without source routing first and
retries with source routing enabled if no
reply was received.
ArpUseEtherSNAP
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False or True)
Default: 0 (False)
Description: If you set this parameter to 1,
TCP/IP transmits Ethernet packets
using 802.3 SNAP encoding. By default, the
stack transmits packets in DIX Ethernet
format. It will always receive both formats.
DefaultTTL
Key: Tcpip\Parameters
Value Type: REG_DWORD - Number of
seconds/hops
Valid Range: 1-255
Default: 128 for Windows XP
Description: This parameter specifies the default Time To
Live (TTL) value that is set in the header of
outgoing IP packets. The TTL determines the
maximum time that an IP packet can live
in the network without reaching its
destination. It is effectively a limit on the
number of routers an IP packet can pass
through before it is discarded.
EnableDeadGWDetect
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False, True)
Default: 1 (True)
Description: If you set this parameter to 1,
TCP uses the Dead Gateway Detection feature.
With this feature, TCP requests IP to
change to a backup gateway if it retransmits
a segment several times without receiving a
response. Backup gateways may be defined in
the Advanced section of the TCP/IP
configuration dialog box in the Network Control
Panel.
EnablePMTUBHDetect
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False, True)
Default: 0 (False)
Description: If you set this parameter to 1
(True), TCP tries to detect "Black
Hole" routers while doing Path MTU Discovery.
A "Black Hole" router does not return ICMP
Destination Unreachable messages when it
must fragment an IP datagram with the
Don't Fragment bit set. TCP must
receive these messages to perform Path MTU
Discovery. With this feature enabled, TCP
will try to send segments without the Don't
Fragment bit set if several retransmissions
of a segment are unacknowledged. If the
segment is acknowledged, the MSS
will be decreased and the Don't Fragment bit
will be set in future packets on the
connection. Enabling black hole detection
increases the maximum number of
retransmissions that are performed for a particular
segment.
EnablePMTUDiscovery
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False, True)
Default: 1 (True)
Description: If you set this parameter to 1
(True), TCP tries to discover the
Maximum Transmission Unit (MTU or largest
packet size) over the path to a remote host.
By discovering the Path MTU and limiting TCP
segments to this size, TCP can eliminate
fragmentation at routers along the path that
connect networks with different MTUs.
Fragmentation adversely affects TCP
throughput and causes network congestion. If you set
this parameter to 0, an MTU of 576
bytes is used for all connections that are
not to computers on the local subnet.
ForwardBufferMemory
Key: Tcpip\Parameters
Value Type: REG_DWORD - Number of bytes
Valid Range: network MTU - some reasonable
value smaller than 0xFFFFFFFF
Default: 74240 (sufficient for fifty 1480-byte
packets, rounded to a multiple of 256)
Description: This parameter determines how
much memory IP allocates to store packet data
in the router packet queue. When this buffer
space is filled, the router starts to discard
packets at random from its queue. Packet
queue data buffers are 256 bytes in length. Therefore, the value of this parameter must be a
multiple of 256. Multiple buffers are chained
together for larger packets. The IP header
for a packet is stored separately. This
parameter is ignored and no buffers are
allocated if the IP router is not enabled.
IGMPLevel
Key: Tcpip\Parameters
Value Type: REG_DWORD - Number
Valid Range: 0,1,2
Default: 2
Description: This parameter determines how well the computer supports IP
multicasting and participates in the Internet
Group Management Protocol. At level 0, the
computer provides no multicast support. At
level 1, the computer can only send IP
multicast packets. At level 2, the computer can
send IP multicast packets and fully
participate in IGMP to receive multicast
packets.
KeepAliveInterval
Key: Tcpip\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 1 - 0xFFFFFFFF
Default: 1000 (one second)
Description: This parameter determines the
interval that separates keepalive
retransmissions until a response is received.
After a response is received, KeepAliveTime again controls the delay until
the next keepalive transmission. The
connection is aborted after the number
of retransmissions that are specified by
TcpMaxDataRetransmissions are
unanswered.
KeepAliveTime
Key: Tcpip\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 1 - 0xFFFFFFFF
Default: 7,200,000 (two hours)
Description: The parameter controls how frequently
TCP tries to verify that an idle
connection is still intact by sending a
keepalive packet. If the remote computer is
still reachable and functioning, the remote computer
acknowledges the keepalive transmission.
By default, keepalive packets are not sent.
A program can turn on this feature
on a connection.
MTU
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD Number
Valid Range: 68 - the MTU of the underlying
network
Default: 0xFFFFFFFF
Description: This parameter overrides the
default Maximum Transmission Unit (MTU) for a
network interface. The MTU is the maximum
packet size in bytes that the transport transmits over the underlying network. The
size includes the transport header. An IP datagram can span multiple packets.
Values larger than the default value for the
underlying network cause the
transport to use the network default MTU.
Values smaller than 68 cause the
transport to use an MTU of 68.
NumForwardPackets
Key: Tcpip\Parameters
Value Type: REG_DWORD Number
Valid Range: 1 - some reasonable value
smaller than 0xFFFFFFFF
Default: 50
Description: This parameter determines the
number of IP packet headers that are allocated for the
router packet queue. When all headers are in
use, the router begins to discard packets
at random from the queue. This value should
be at least as large as the
ForwardBufferMemory value divided by the
maximum IP data size of the networks that are
connected to the router. This value must be no
larger than the ForwardBufferMemory value
divided by 256 because at least 256 bytes of
forward buffer memory are used for each
packet. The optimal number of forward packets
for a particular ForwardBufferMemory size depends
on the type of traffic that is carried on the network
and will be somewhere between these two
values. This parameter is ignored and no
headers are allocated if the router is not
enabled.
TcpMaxConnectRetransmissions
Key: Tcpip\Parameters
Value Type: REG_DWORD - Number
Valid Range: 0 - 0xFFFFFFFF
Default: 2
Description: This parameter determines the
number of times that TCP retransmits a connect
request (SYN) before aborting the attempt.
The retransmission timeout is doubled with
each successive retransmission in a particular
connect attempt. The initial timeout value is
three seconds.
TcpUseRFC1122UrgentPointer
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0,1 (False, True)
Default: 0 (False)
Description: This parameter determines
whether TCP uses the RFC 1122 specification
for urgent data or the mode that is used by BSD-derived computers. The two mechanisms interpret
the urgent pointer in the TCP header and the
length of the urgent data differently. They
are not interoperable. By default, Windows XP uses the
BSD mode.
TcpWindowSize
Key: Tcpip\Parameters
Value Type: REG_DWORD - Number of bytes
Valid Range: 0 - 0xFFFF
Default: The smaller of 0xFFFF
OR
(The larger of four times the maximum TCP
data size on the network
OR
8192 rounded up to an even multiple of the
network TCP data size.)
The default is 8760 for Ethernet.
Description: This parameter determines the
maximum TCP receive window size of
the computer. The receive window specifies the
number of bytes a sender can transmit without
receiving an acknowledgment. Generally,
larger receive windows improve
performance over high (delay * bandwidth)
networks. For highest efficiency, the receive
window must be an even multiple of the TCP
Maximum Segment Size (MSS).
Parameters that are configurable from the properties of a network connection
The following parameters are created and modified automatically by the
connection properties interface through user-supplied information.
You do not have to configure them directly in the registry.
DefaultGateway
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_MULTI_SZ - List of dotted
decimal IP addresses
Valid Range: Any set of valid IP addresses
Default: None
Description: This parameter specifies the
list of gateways to route packets
that are not destined for a subnet that the computer
is directly connected to and that do not have a
more specific route. This
parameter overrides
the DhcpDefaultGateway parameter.
Domain
Key: Tcpip\Parameters
Value Type: REG_SZ - Character string
Valid Range: Any valid DNS domain name
Default: None
Description: This parameter specifies the DNS
domain name of the computer. It is used by the
Windows Sockets interface.
EnableDhcp
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: If this parameter is set to 1
(True), the DHCP client service tries to use DHCP to configure the first IP interface
on the adapter.
Hostname
Key: Tcpip\Parameters
Value Type: REG_SZ - Character string
Valid Range: Any valid DNS hostname
Default: The computer name of the computer
Description: This parameter specifies the DNS
hostname of the computer that will be returned
by the hostname command.
IPAddress
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_MULTI_SZ - List of dotted-
decimal IP addresses
Valid Range: Any set of valid IP addresses
Default: None
Description: This parameter specifies the IP
addresses of the IP interfaces to be bound to
the adapter. If the first address in the list
is 0.0.0.0, the primary interface on the
adapter will be configured from DHCP. A
computer with more than one IP interface for an
adapter is known as "logically multihomed."
There must be a valid subnet mask value in
the SubnetMask parameter for each IP address
that is specified in this parameter.
IPEnableRouter
Key: Tcpip\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: Setting this parameter to 1
(True) causes the computer to route IP packets
between the networks that it is connected to.
NameServer
Key: Tcpip\Parameters
Value Type: REG_SZ - A space delimited list
of dotted decimal IP addresses
Valid Range: Any set of valid IP address
Default: None (Blank)
Description: This parameter specifies the DNS
name servers to be queried by Windows Sockets
to resolve names.
SearchList
Key: Tcpip\Parameters
Value Type: REG_SZ - Delimited list of
DNS domain name suffixes
Valid Range: Any set of valid DNS domain name
suffixes
Valid Range: Any set of valid DNS domain name suffixes
Default: None
Description: This parameter specifies a list
of domain name suffixes to append to a name
to be resolved by the DNS if resolution of
the unadorned name fails. By default, the
value of the Domain parameter is appended
only. This parameter is used by the Windows
Sockets interface.
SubnetMask
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_MULTI_SZ - List of dotted
decimal IP addresses
Valid Range: Any set of valid IP addresses.
Default: None
Description: This parameter specifies the
subnet masks to be used with the IP
interfaces bound to the adapter. If the first
mask in the list is 0.0.0.0, the primary
interface on the adapter will be configured
by DHCP. There must be a valid subnet mask
value in this parameter for each IP address
that is specified in the IPAddress parameter.
Non-configurable parameters
The following parameters are created and used internally by the TCP/IP components. They should never be modified by using Registry Editor. They are listed here for reference only.
DhcpDefaultGateway
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_MULTI_SZ - List of dotted
decimal IP addresses
Valid Range: Any set of valid IP addresses
Default: None
Description: This parameter specifies the
list of default gateways to route
packets that are not destined for a subnet that the
computer is directly connected to, and that do not have a more specific route.
This parameter is written by the DHCP client
service, if enabled. This parameter is
overridden by a valid DefaultGateway
parameter value.
DhcpIPAddress
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address
Valid Range: Any valid IP address
Default: None
Description: This parameter specifies the
DHCP-configured IP address for the interface.
If the IPAddress parameter contains a first
value other than 0.0.0.0, that value
will override this parameter.
DhcpNameServer
Key: Tcpip\Parameters
Value Type: REG_SZ - A space delimited list
of dotted decimal IP addresses
Valid Range: Any set of valid IP address
Default: None
Description: This parameter specifies the DNS
name servers to be queried by Windows Sockets
to resolve names. It is written by the DHCP
client service, if enabled. The NameServer
parameter overrides this parameter.
DhcpServer
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address
Valid Range: Any valid IP address
Default: None
Description: This parameter specifies the IP
address of the DHCP server that granted the
lease on the IP address in the DhcpIPAddress
parameter.
DhcpSubnetMask
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_SZ - Dotted decimal IP subnet
mask
Valid Range: Any subnet mask that is valid
for the configured IP address
Default: None
Description: This parameter specifies the
DHCP-configured subnet mask for the address
that is specified in the DhcpIPAddress parameter.
IPInterfaceContext
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD
Valid Range: 0 - 0xFFFFFFFF
Default: None
Description: This parameter is written by the
TCP/IP driver for use by the DHCP client
service.
Lease
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Time in seconds
Valid Range: 1 - 0xFFFFFFFF
Default: None
Description: This parameter is used by the
DHCP client service to store the time (in
seconds) that the lease on the IP address for
this adapter is valid for.
LeaseObtainedTime
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Absolute time in
seconds since midnight of 1/1/70
Valid Range: 1 - 0xFFFFFFFF
Default: None
Description: This parameter is used by the
DHCP client service to store the time that the lease on the IP address for this
adapter obtained.
LeaseTerminatesTime
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Absolute time in
seconds since midnight of 1/1/70
Valid Range: 1 - 0xFFFFFFFF
Default: None
Description: This parameter is used by the
DHCP client service to store the time that the lease on the IP address for this
adapter expires.
LLInterface
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_SZ - NT device name
Valid Range: A valid NT device name
Default: Empty string (Blank)
Description: This parameter is used to direct
IP to bind to a different link-layer protocol
than the built-in ARP module. The value of the
parameter is the name of the Windows NT-based
device that IP should bind to. This parameter
is used in conjunction with the RAS component,
for example.
T1
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Absolute time in
seconds since midnight of 1/1/70
Valid Range: 1 - 0xFFFFFFFF
Default: None
Description: This parameter is used by the
DHCP client service to store the time that the service will first try to renew the
lease on the IP address for the adapter. To renew the lease, he service contacts the server that granted the lease.
T2
Key: Tcpip\Parameters\Interfaces\ID for Adapter
Value Type: REG_DWORD - Absolute time in
seconds since midnight of 1/1/70
Valid Range: 1 - 0xFFFFFFFF
Default: None
Description: This parameter is used by the
DHCP client service to store the time that the service will try to renew the lease
on the IP address for the adapter. To renew the lease, the service broadcasts a renewal request. Time T2
should be reached only if the service was not able to renew the lease with the
original server.
NBT
all the NBT parameters are registry values that are located under one of two different subkeys of
HKEY_LOCAL_MACHINE\computer\CurrentControlSet\Services
Netbt\Parameters
Netbt\Parameters\Interfaces\Tcpip_ID for Adapter
where
ID for Adapter represents the network adapter that NBT is bound to. The relationship between an Adapter ID and Network Connection can be determined by examining HKEY_LOCAL_MACHINE\computer\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\
ID for Adapter\Connection. The Name value in these keys provides the name that is used for a network connection used in the Network Connections folder.
Values under the latter keys are specific to each adapter. If the computer is configured through DHCP, a change in parameters takes effect if the command
ipconfig /renew is issued in a command shell. Otherwise, you must restart the computer for a change in any of these parameters to take effect.
Standard Parameters Configurable from Registry Editor
The following parameters are installed with default values by the Network tool in Control Panel
during the installation of the TCP/IP components. They may be modified by
using Registry Editor (Regedit.exe).
BcastNameQueryCount
Key: Netbt\Parameters
Value Type: REG_DWORD - Count
Valid Range: 1 to 0xFFFF
Default: 3
Description: This value determines the number of times NetBT broadcasts a query for a particular
name without receiving a response.
BcastQueryTimeout
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 100 to 0xFFFFFFFF
Default: 0x2ee ( 750 decimal)
Description: This value determines the time
interval between successive broadcast name
queries for the same name.
CacheTimeout
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 60000 to 0xFFFFFFFF
Default: 0x927c0 ( 600000 milliseconds = 10
minutes)
Description: This value determines the time
interval that names are cached for in the remote
name table.
NameServerPort
Key: Netbt\Parameters
Value Type: REG_DWORD - UDP port number
Valid Range: 0 - 0xFFFF
Default: 0x89
Description: This parameter determines the
destination port number that NetBT sends
packets to that are related to name service, such as
name queries and name registrations to WINS.
The Microsoft WINS listens on port 0x89.
NetBIOS name servers from other vendors can
listen on different ports.
NameSrvQueryCount
Key: Netbt\Parameters
Value Type: REG_DWORD - Count
Valid Range: 0 - 0xFFFF
Default: 3
Description: This value determines the number
of times NetBT sends a query to a WINS server
for a specified name without receiving a
response.
NameSrvQueryTimeout
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 100 - 0xFFFFFFFF
Default: 1500 (1.5 seconds)
Description: This value determines the time
interval between successive name queries to
WINS for a particular name.
SessionKeepAlive
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 60,000 - 0xFFFFFFFF
Default: 3,600,000 (1 hour)
Description: This value determines the time
interval between keepalive transmissions on a
session. Setting the value to 0xFFFFFFF
disables keepalives.
Size/Small/Medium/Large
Key: Netbt\Parameters
Value Type: REG_DWORD
Valid Range: 1, 2, 3 (Small, Medium, Large)
Default: 1 (Small)
Description: This value determines the size
of the name tables that are used to store local and
remote names. Generally, Small is adequate.
If the computer is acting as a proxy
name server, the value is automatically
set to Large to increase the size of the name
cache hash table. Hash table buckets are
sized as follows:
Large: 256 Medium: 128 Small: 16
Optional Parameters Configurable from Registry Editor
These parameters generally do not exist in the registry. They may be
created
to modify the default behavior of the NetBT protocol driver.
BroadcastAddress
Key: Netbt\Parameters
Value Type: REG_DWORD - Four byte, little-
endian encoded IP address
Valid Range: 0 - 0xFFFFFFFF
Default: The ones-broadcast address for each
network.
Description: This parameter can be used to
force NetBT to use a specific address for all
broadcast name-related packets. By default,
NetBT uses the ones-broadcast address that is
appropriate for each net (that is, for a network
of 11.101.0.0 with a subnet mask of
255.255.0.0, the subnet broadcast address
would be 11.101.255.255). This parameter
would be set, for example, if the network
uses the zeros-broadcast address (set by using
the UseZeroBroadcast TCP/IP parameter). The
appropriate subnet broadcast address would
then be 11.101.0.0 in the earlier example. This
parameter would then be set to 0x0b650000.
This parameter is global and is
used on all subnets that NetBT is bound to.
EnableProxy
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: If this value is set to 1
(True), the computer acts as a proxy
name server for the networks that NBT is
bound to. A proxy name server answers
broadcast queries for names that it has
resolved through WINS. With a proxy name server,
a network of B-node implementations can
connect to servers on other subnets that are
registered with WINS.
EnableProxyRegCheck
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: If this parameter is set to 1
(True), the proxy name server sends
a negative response to a broadcast name
registration if the name is already
registered with WINS or is in the proxy's
local name cache with a different IP address.
The hazard of enabling this feature is that
it prevents a computer from changing its IP
address as long as WINS has a mapping for the
name. Therefore, it is disabled by
default.
InitialRefreshT.O.
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 960000 - 0xFFFFFFF
Default: 960000 (16 minutes)
Description: This parameter specifies the
initial update timeout used by NBT during
name registration. NBT tries to contact the
WINS servers at 1/8th of this time interval
when it is first registering names. When it
receives a successful registration response,
that response contains the new update
interval to use.
LmhostsTimeout
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 1000 - 0xFFFFFFFF
Default: 6000 (6 seconds)
Description: This parameter specifies the
timeout value for LMHOSTS and DNS name
queries. The timer has a granularity of the
timeout value. Therefore, the actual timeout might be
as much as two times the value.
MaxDgramBuffering
Key: Netbt\Parameters
Value Type: REG_DWORD - Count of bytes
Valid Range: 0 - 0xFFFFFFFF
Default: 0x20000 (128 Kb)
Description: This parameter specifies the
maximum memory that NetBT
dynamically allocates for all outstanding
datagram sends. After this limit is reached,
additional sends will fail because the available resources are not sufficient
resources.
NodeType
Key: Netbt\Parameters
Value Type: REG_DWORD - Number
Valid Range: 1,2,4,8 (B-node, P-node, M-node,
H-node)
Default: 1 or 8 based on the WINS server
configuration
Description: This parameter determines what
methods NetBT uses to register and
resolve names. A B-node computer uses
broadcasts. A P-node computer uses only point-
to-point name queries to a name server
(WINS). An M-node computer broadcasts first, and
then queries the name server. An H-node
computer queries the name server first, and then
broadcasts. Resolution through LMHOSTS or
DNS follows these
methods. If this key is present, it will
override the DhcpNodeType key. If neither key
is present, the computer uses B-node if
there are no WINS servers configured for the
network. The computer uses H-node if
there is at least one WINS server configured.
RandomAdapter
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: This parameter applies to a
multihomed host only. If it is set to 1
(True), NetBT will randomly select the
IP address to put in a name query response
from all its bound interfaces. Frequently,
the response contains the address of the
interface that the query arrived on. This
feature would be used by a server with two
interfaces on the same network for load
balancing.
RefreshOpCode
Key: Netbt\Parameters
Value Type: REG_DWORD - Number
Valid Range: 8, 9
Default: 8
Description: This parameter forces NetBT to
use a specific opcode in name update
packets. The specification for the NetBT
protocol is somewhat ambiguous in this area.
Although the default of 8 that is used by Microsoft
implementations appears to be the intended
value, some other implementations, such as
those by Ungermann-Bass, use the value 9. Two
implementations must use the same opcode to
interoperate.
SingleResponse
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: This parameter applies to a
multihomed host only. If this parameter is
set to 1 (True), NBT will only supply an
IP address from one of its bound interfaces
in name query responses. By default, the
addresses of all bound interfaces are
included.
WinsDownTimeout
Key: Netbt\Parameters
Value Type: REG_DWORD - Time in milliseconds
Valid Range: 1000 - 0xFFFFFFFF
Default: 15,000 ( 15 seconds)
Description: This parameter determines the
time that NBT waits before again
trying to use WINS after it does not contact
any WINS server. With this feature, computers that are temporarily
disconnected from the network can proceed through boot processing
without waiting to time out each WINS name
registration or query individually.
Parameters Configurable from the Connection Properties
The following parameters can be set through the Connection Properties from the Network Connections folder. You do not have to configure them directly.
EnableDns
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 0 (False)
Description: If this value is set to 1
(True), NBT queries the DNS for names
that cannot be resolved by WINS, broadcast,
or the LMHOSTS file.
EnableLmhosts
Key: Netbt\Parameters
Value Type: REG_DWORD - Boolean
Valid Range: 0 or 1 (False or True)
Default: 1 (True)
Description: If this value is set to 1
(True), NBT searches the LMHOSTS
file, if it exists, for names that cannot be
resolved by WINS or broadcast. By default,
there is no LMHOSTS file database directory
(specified by Tcpip\Parameters\DatabasePath). Therefore, NBT takes no action. This value is
written by the Advanced TCP/IP configuration
under the Network tool in Control Panel.
NameServer
Key: Netbt\Parameters\Interfaces\Tcpip_ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address (for example,11.101.1.200)
Valid Range: Any valid IP address
Default: blank ( no address )
Description: This parameter specifies the IP
address of the primary WINS server. If this
parameter contains a valid value, it
overrides the DHCP parameter of the same
name.
NameServerBackup
Key: Netbt\Parameters\Interfaces\Tcpip_ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address (for example, 11.101.1.200)
Valid Range: Any valid IP address.
Default: blank ( no address )
Description: This parameter specifies the IP
address of the backup WINS server. If this
parameter contains a valid value, it
overrides the DHCP parameter of the same
name.
ScopeId
Key: Netbt\Parameters
Value Type: REG_SZ - Character string
Valid Range: Any valid DNS domain name
consisting of two dot-separated parts, or a
"*".
Default: None
Description: This parameter specifies the
NetBIOS name scope for the node. This value
must not start with a period. If this
parameter contains a valid value, it will
override the DHCP parameter of the same name.
A blank value (empty string) will be ignored.
Setting this parameter to the value "*"
indicates a null scope and will override the
DHCP parameter.
Non-Configurable Parameters
The following parameters are created and used internally by the NetBT
components. They should never be modified by using Registry Editor. They
are listed here for reference only.
DhcpNameServer
Key: Netbt\Parameters\Interfaces\Tcpip_ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address (for example, 11.101.1.200)
Valid Range: Any valid IP address
Default: None
Description: This parameter specifies the IP
address of the primary WINS server. It is
written by the DHCP client service, if
enabled. A valid NameServer value will
override this parameter.
DhcpNameServerBackup
Key: Netbt\Parameters\Interfaces\Tcpip_ID for Adapter
Value Type: REG_SZ - Dotted decimal IP
address (for example, 11.101.1.200)
Valid Range: Any valid IP address
Default: None
Description: This parameter specifies the IP
address of the backup WINS server. It is
written by the DHCP client service, if
enabled. A valid BackupNameServer value will
override this parameter.
DhcpNodeType
Key: Netbt\Parameters
Value Type: REG_DWORD - Number
Valid Range: 1 - 8
Default: 1
Description: This parameter specifies the NBT
node type. It is written by the DHCP client service, if enabled. A valid NodeType value
will override this parameter. See the entry
for NodeType for a complete description.
DhcpScopeId
Key: Netbt\Parameters
Value Type: REG_SZ - Character string
Valid Range: a dot-separated name string such
as "microsoft.com"
Default: None
Description: This parameter specifies the
NetBIOS name scope for the node. It is
written by the DHCP client service, if
enabled. This value must not start with a
period. See the entry for ScopeId for more
information.
NbProvider
Key: Netbt\Parameters
Value Type: REG_SZ - Character string
Valid Range: _tcp
Default: _tcp
Description: This parameter is used
internally by the RPC component. The default
value should not be changed.
TransportBindName
Key: Netbt\Parameters
Value Type: REG_SZ - Character string
Valid Range: N/A
Default: \Device\
Description: This parameter is used
internally during product development. The
default value should not be changed.