IPConfig

IPConfig is a command-line tool that displays the current configuration of the installed IP stack on a networked computer. Run IPConfig whenever you need to know the status of a computer's TCP/IP configuration. Start IPConfig from the command prompt rather than from Windows Explorer to see the resulting display.

Since the results fill more than one normal command prompt screen when you use the /all switch, you might wish to redirect the output to a text file which can be viewed later in Notepad. To redirect IPConfig's screen output to a text file type:

ipconfig /all > ipconfig.txt

Run IPConfig whenever you need to know the status of a computer's TCP/IP configuration. When used with the /all switch, it displays a detailed configuration report for all interfaces, including any configured wide area networks (WAN) miniports (typically used for remote access or VPN connections). The following is a sample report:

Windows 2000 IP Configuration

Host Name . . . . . . . . . . . . : TESTPC1

Primary Domain Name . . . . . . . : reskit.com

Node Type . . . . . . . . . . . . : Hybrid

IP Routing Enabled. . . . . . . . : No

WINS Proxy Enabled. . . . . . . . : No

DNS Suffix Search List. . . . . . : ntcorpdc1.reskit.com

dns.reskit.com

reskit.com

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : dns.microsoft.com

Description . . . . . . . . . . . : Acme XL 10/100Mb Ethernet NIC

Physical Address. . . . . . . . . : 00-CC-44-79-C3-AA

DHCP Enabled. . . . . . . . . . . : Yes

Autoconfiguration Enabled . . . . : Yes

IP Address. . . . . . . . . . . . : 172.16.245.111

Subnet Mask . . . . . . . . . . . : 255.255.248.0

Default Gateway . . . . . . . . . : 172.16.240.1

DHCP Server . . . . . . . . . . . : 172.16.248.8

DNS Servers . . . . . . . . . . . : 172.16.55.85

172.16.55.134

172.16.55.54

Primary WINS Server . . . . . . . : 172.16.248.10

Secondary WINS Server . . . . . . : 172.16.248.9

Lease Obtained. . . . . . . . . . : Friday, March 05, 1999 2:21:40 PM

Lease Expires . . . . . . . . . . : Sunday, March 07, 1999 2:21:40 PM

A number of other useful switches for IPConfig include /flushdns , which deletes the DNS name cache; /registerdns , which refreshes all Dynamic Host Configuration Protocol (DHCP) leases and re-registers DNS names; and /displaydns which displays the contents of the DNS resolver cache.

The /release < adapter > and /renew < adapter > options release and renew the DHCP-allocated IP address for a specified adapter. If no adapter name is specified, the DHCP leases for all adapters bound to TCP/IP are released or renewed. Table 14.5 lists all IPConfig switches.

Table   14.5 IPConfig Switches

Switch	Effect
/all	Produces a detailed configuration report for all interfaces.
/release < adapter >	Releases the IP address for a specified adapter.
/renew < adapter >	Renew the IP address for the specified adapter.
/flushdns	Removes all entries from the DNS Resolver Cache.
/registerdns	Refreshes all DHCP leases and reregisters DNS names.
/displaydns	Displays the contents of the DNS Resolver Cache.
/showclassid adapter	Displays all the DHCP class IDs allowed for the adapter specified.
/setclassid adapter	Modifies the DHCP class ID for the adapter specified.
/?	Displays this list.

Caution

Many of the advanced features of IPConfig must not be used on a client system without the assistance of a network administrator or support personnel. Using these commands incorrectly can cause problems with the client system's connection to the server.