How to renew IP address, Routing and flush DNS
cache on Windows XP / Vista / 7
There are two handy Windows commands which can be used to renew IP
address or flush prior cached DNS records which often create
problems with resolving hosts.
1. To renew the IP address (fetch address from DHCP server)
C:\> ipconfig /release
C:\> ipconfig /renew
In above cmd
ipconfig /release will de-assign the IP address
configured on all Windows LAN and Wireless interfaces, whether
ipconfig /renew will send request for IP address to the DNS
server.
To unassign and assign again IP address from DHCP server only for a
particular LAN or WLAN card:
C:\> ipconfig /release LAN
C:\> ipconfig /renew LAN
C:\> ipconfig /release WLAN
C:\> ipconfig /renew WLAN
2. Adding specific routing to Windows
Windows has a
Route command similar by syntax to Linux's
route command.
To add routing via a specific predefined IP addresses on Windows
the commands should be something like:
C:> Route add 192.168.40.0 mask 255.255.255.0
192.168.41.253
C:> Route add 0.0.0.0 mask 0.0.0.0 192.168.41.254
The first command adds IP
192.168.40.0 in the network of 255
hosts to be routed via
192.168.41.253
The second one adds
192.168.41.254 as a default gateway for
all outbound traffic from the Windows host.
To make permanent routing
-p switch is used.
3. To clear Windows DNS cache (flush DNS cached records)
C:\> ipconfig /flushdns
This will clear all IP records corresponding to hostnames
previously cached on the Windows host. Using ipconfig /flushdns is
especially handy when IP address for a specific DNS host is
changed. Flushing the Windows DNS cache can save us a lot of
waiting before the domain
example.com starts resolving to
the new IP address let's say
1.2.3.4 instead of the old one
2.2.2.2