When you transfer your domain from one host to another, you change your nameserver configuration. But the problem is that sometimes it takes a while for the nameserver change to propagate through the DNS server of your ISP. Sometime the DNS configuration is cached on your computer or browser session. Here are some tips to remove DNS cache and also to see hosting server changes immediately.

Clearing DNS Cache on Microsoft Windows

From the command prompt (start=>run=>cmd) enter the command ipconfig/flushdns. This will purge the DNS resolver cache.

This will remove dns cache entries from your machine. But you will still have a problem if your ISP DNS cache is holding the old DNS entry. There is a simple trick to bypass DNS mechanism in Windows.

Search for the file named “hosts” inside Windows folder. In my Windows Vista machine this is located inside c:\windows\system32\drivers. Add a new line like the one below(replace domain with your domain and IP address with the IP address of the Web host machine where your domain is relocated).

www.dailytechnotes.com   74.53.227.162

“hosts” is first searched by Windows to resolve a domain to an IP address effectively short circuiting the ISP DNS.

Clearing DNS cache on Linux

On linux you can use the command sudo /etc/init.d/nscd restart  to clear DNS cache. This assumes that nscd is already installed in your linux box.  On ubuntu you can try restarting the networking service using the command sudo /etc/init.d/networking restart.

The above mentioned Windows trick can also be applied on linux machines. In linux you need to modify /etc/hosts file and add your domain and domain hosted server ip as given below. You need restart the networking using sudo /etc/init.d/networking restart for this to work.

www.dailytechnotes.com   74.53.227.162

Clearing DNS cache on Mac

On a Mac OS X you can clear DNS cache by typing the command lookupd -flushcache.

Clearing DNS cache from browsers

DNS is also cached at browsers. Most of the time this is cleared when you close all the browser sessions. In Firefox this can be forced by clearing the private data from tools menu.

If you are using your own WiFi router and if you forget the WEP or WPA key, the easiest option is to create a new key! After all you have complete access to your router!

But what if you are connecting to an external WiFi router? The problem is once you enter the key, Windows remembers the key for the network and it won’t ask again. After a couple of days you have forgotten the key. You still have access to wireless network, but you want to find the key Windows is using so that you can back it up! Another scenario is when you want to configure the same wireless network on a different machine.

Fortunately there is a freeware tool(WirelessKeyView) which can display WEP/WPA wireless keys stored by Windows. You can download WirelessKeyView from here.  You can see this software in action below.

This utility can recover network key only if it is stored by ‘Wireless Zero Configuration’ service of Windows XP and by the ‘WLAN AutoConfig’ service of Windows Vista. Also note that you need to have administrator access to machine for this to work!

Programs such as this work using Windows API which expose WEP/WPA keys!