ipconfig

ipconfig

---

Displays the current TCP/IP settings of the local machine.

Syntax

 ipconfig [/all  /release [   adaptername   ]  [/renew [   adaptername   ]  /flushdns   /displaydns  /registerdns  /showclassid   adaptername   /setclassid   adaptername   [   newclassID   ]] 

Options

None

Displays the IP address, subnet mask, and default gateway for each interface on the machine.

/all

Yields verbose output showing additional TCP/IP settings.

/release [adaptername]

Releases an IP address acquired using DHCP. On a multihomed machine, specify an adapter name using the name that appears for the adapter when you type ipconfig without parameters.

/renew [adaptername]

Requests a new IP address from a DHCP server (available only when the computer is configured as a DHCP client)

/displaydns

Displays the contents of the local DNS name cache on the client. When DNS resolves a DNS name into an IP address, the results are temporarily cached.

/flushdns

Flushes the list of locally cached DNS names on the client. Flushing the cache removes these mappings and can be useful when troubleshooting DNS- related problems. Flushing the DNS cache on the client doesn't remove mappings that have been preloaded from the local Hosts file. (You must remove these mappings from the Hosts file to do this.)

/registerdns

Causes the client to reregister its hostname with DNS servers without restarting the client machine. This may also be used with Dynamic DNS.

/showclassid adaptername

Displays all the DHCP class IDs allowed for the adapter. WS2003 DHCP clients support DHCP class options that can be viewed using this command and configured using ipconfig /setclassid .

/setclassid adaptername [newclassID]

Changes the DHCP class ID for the adapter.

Examples

Display summary of TCP/IP settings on local machine:

  ipconfig  Windows IP Configuration Ethernet adapter Local Area Connection:    Connection-specific DNS Suffix  . :    IP Address. . . . . . . . . . . . : 172.16.11.105    Subnet Mask . . . . . . . . . . . : 255.255.255.0    IP Address. . . . . . . . . . . . : 172.16.11.104    Subnet Mask . . . . . . . . . . . : 255.255.255.0    Default Gateway . . . . . . . . . : 172.16.11.196 

Display full details:

  ipconfig /all  Windows IP Configuration    Host Name . . . . . . . . . . . . : test    Primary DNS Suffix  . . . . . . . : mtitcanada.com    Node Type . . . . . . . . . . . . : Hybrid    IP Routing Enabled. . . . . . . . : No    WINS Proxy Enabled. . . . . . . . : No    DNS Suffix Search List. . . . . . : mtitcanada.com Ethernet adapter Local Area Connection:  Connection-specific DNS Suffix  . :  Description . . . . . . . . . . . : Realtek                 RTL8029(AS) PCI Ethernet Adapter  Physical Address. . . . . . . . . : 00-00-B4-A0-47-74  DHCP Enabled. . . . . . . . . . . : No  IP Address. . . . . . . . . . . . : 172.16.11.105  Subnet Mask . . . . . . . . . . . : 255.255.255.0  IP Address. . . . . . . . . . . . : 172.16.11.104  Subnet Mask . . . . . . . . . . . : 255.255.255.0  Default Gateway . . . . . . . . . : 172.16.11.196  DNS Servers . . . . . . . . . . . : 172.16.11.104                                      172.16.11.100 

Display contents of client DNS name cache:

  ipconfig /displaydns  Windows IP Configuration        localhost.    --------------------------------------------------      Record Name . . . . . : localhost      Record Type . . . . . : 1      Time To Live  . . . . : 31338848      Data Length . . . . . : 4      Section . . . . . . . : Answer      A (Host) Record . . . :                        127.0.0.1        1.0.0.127.in-addr.arpa.    --------------------------------------------------      Record Name . . . . . : 1.0.0.127.in-addr.arpa      Record Type . . . . . : 12      Time To Live  . . . . : 31338847      Data Length . . . . . : 4      Section . . . . . . . : Answer      PTR Record  . . . . . :                        localhost        bach.mtitworld.com.    --------------------------------------------------      Record Name . . . . . : bach.mtitworld.com      Record Type . . . . . : 1      Time To Live  . . . . : 261      Data Length . . . . . : 4      Section . . . . . . . : Answer      A (Host) Record . . . :                        172.16.11.100        test.mtitcanada.com.    --------------------------------------------------      Record Name . . . . . : test.mtitcanada.com      Record Type . . . . . : 1      Time To Live  . . . . : 2665      Data Length . . . . . : 4      Section . . . . . . . : Answer      A (Host) Record . . . :                        172.16.11.104          Record Name . . . . . : test.mtitcanada.com      Record Type . . . . . : 1      Time To Live  . . . . : 2665      Data Length . . . . . : 4      Section . . . . . . . : Answer      A (Host) Record . . . :                        172.16.11.105 

Flush client DNS name cache:

  ipconfig /flushdns  Windows IP Configuration Successfully flushed the DNS Resolver Cache. 

Verify that client DNS name cache has been flushed:

  ipconfig /displaydns  Windows IP Configuration        localhost.    --------------------------------------------------      Record Name . . . . . : localhost      Record Type . . . . . : 1      Time To Live  . . . . : 31338835      Data Length . . . . . : 4      Section . . . . . . . : Answer      A (Host) Record . . . :                        127.0.0.1 

Note the mapping that remains in the cache. This is preloaded from the Hosts file on the client.

Reregister client's DNS information with DNS server:

  ipconfig /registerdns  Windows IP Configuration Registration of the DNS resource records for all adapters of this computer  has been initiated. Any errors will be reported in the Event Viewer in 15  minutes. 

Display DHCP class IDs for the client on the "Local-Area Connection" adapter:

  ipconfig showclassid "Local Area Connection"  Windows IP Configuration DHCP Class ID for Adapter "Local Area Connection": DHCP ClassID Name . . . . . . . . : Default BOOTP Class DHCP ClassID Description  . . . . : User class for BOOTP Clients 

Notes

The DNS name cache in WS2003 also supports negative caching of unresolved or invalid DNS names. However, these negative DNS responses are cached for only a short period of time.

See Also

DNS , ping , TCP/IP