Before telling about flushdns let me first tell you about IP address,Dns....
Any computer connected to internet has a unique address called as IP address.It is a 32 bit address in the form xx.xx.xx.xx where xx takes the values from 0-255.
IP address is similar to our house address .As our house address helps people to xactly pinpoint our location on this earth which helps them to send letters,couriers and to come and meet us directly.In the same way IP address helps to determine the location of a computer so that data is sent exactly to the recipients address.But we humans cannot remember many IP addresses it wud b nice to remember them if the address is denoted in the form of letters and words.
here comes the usage of DNS .
Dns(Domain Naming system):- Dns maps ip addressess to human understandable address for example ip address of google.com is 66.249.89.104.It is easy to remember google.com than remembering this lengthy ip address.Also at times IP referring to a domain may change but domainname remains constant.In such cases domain names are very useful.On the other hand Computers cannot find a computer/host using domain name hence their first step is to convert Domainname into IPaddress .
To do the above step it has to connect to a Dns server known as Primary Dns server requesting what is the ip addresses of this domain name.
Dns server inturn looksup into its table and returns IP address of that paricular domain.If the primary dns server fails to return ip address our computer connects a secondary Dns server which will fiannly give its Ip addresses.
After recieving this IP addrs our system stores these addresses in dnscache for frequent usage .But sometimes due to cache poisoning or some other reason Dns cache doesnot map IP address-domain names correctly so we cannot browse the net.
now wat we hav to do is just "flushdns" thru the command c:\ipconfig /flushdns.
Some times our system responds saying that couldnot flush the dns resolver cache .
This implies that Dns client sevice is not running on our computer .
Now goto "run" type services.msc .Look for a service called DNS client.
Now right click and select properties.Now select startup type as manual or automatic and click on the start button to start the Dns client service.Now our command
c:\ipconfig /flushdns works fine
