Ipconfig
IPConfig is a command-line tool that displays the current configuration of the installed IP stack on a networked computer.
When used with the /all switch, it displays a detailed configuration report for all interfaces, including any configured WAN miniports (typically used for remote access or VPN connections). Output can be redirected to a file and pasted into other documents. A sample report is shown here:
C:>\ipconfig /all
Windows 2000 IP Configuration
Host Name . . . . . . . . . . . . : TESTPC1
Primary DNS Suffix . . . . . . . : 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.reskit.com
Description . . . . . . . . . . . : Acme XL 10/100Mb Ethernet NIC
Physical Address. . . . . . . . . : 00-CC-44-79-C3-AA
DHCP 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, May 05, 1999 2:21:40 PM
Lease Expires . . . . . . . . . . : Monday, May 07, 1999 2:21:40 PM
A number of other useful parameters for Ipconfig include /flushdns , which deletes the DNS name cache; /registerdns , which refreshes all 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.
For /setclassid , if no class ID is specified, then the Class ID is removed. Table 3.3 lists all Ipconfig switches.
Table 3.3 Ipconfig Switches
Switch |
Effect |
|---|---|
/all |
Produces a detailed configuration report for all interfaces. |
/flushdns |
Removes all entries from the DNS name cache. |
/registerdns |
Refreshes all DHCP leases and reregisters DNS names |
/displaydns |
Displays the contents of the DNS resolver cache. |
/release < adapter > |
Releases the IP address for a specified interface. |
/renew < adapter > |
Renews the IP address for a specified interface. |
/showclassid < adapter > |
Displays all the DHCP class IDs allowed for the adapter specified. |
/setclassid < adapter > < classID to set > |
Changes the DHCP class ID for the adapter specified. |
/? |
Displays this list. |
The /showclassid and /setclassid options allow you to manipulate user class IDs from the command line. The user class IDs are options that a system administrator may set on the DHCP server to configure a client computer to identify itself with the server. Issuing the command ipconfig /showclassid < adapter > sends a query to the client's server; the server responds by providing the available classes. Once you know which classes are available, you can issue a command like ipconfig /setdhcpclassid < adapter > < class ID to set on the server > to set the class ID that the client will use from that point on. For more information about DHCP and class IDs, see "Dynamic Host Configuration Protocol" in this book.