i have a old application (wignet) which points to http://rootsite/subsite1 .There are around 10 subsites (subsite2,subsite3,subsite4) .Now i have created a new sp application http://sharepointrootsite/subsite11 and .I want to configure the application in such a way that the users should be redirected to wignet when they type http://rootsite/subsite1 and sharepoint when they type http://sharepointrootsite/subsite11 .is this possible because i have less knowledge of DNS and config ?
The first thing you will need to do is configure an Internal URL in your Alternate Access Mappings for http://rootsite in the zone used by http://sharepointrootsite so that SharePoint knows what to respond to. You might also need to manually add http://rootsite to the host headers in the IIS on the farm hosting http://SharePointrootsite. Those two changes will configure your new farm to respond to the original URL.
However, now you need to direct everyone over to the new farm. To do this, you will need to modify your DNS and change the entry for http://rootsite to point to the IP address of the new farm. The specifics of this will vary by the software\appliance that you are using to manage your DNS with.