I want to redirect http://abc.example.com to other external site abc.blog.com but i dont want to change the url from which i redirected. It should remain the same, i tried using dns but not working.
Kindly guide me with each and every step.
If its possible with htacces then how ?
If you own abc.example.com you can set it up as a CNAME of abc.blog.com, which you'd need to configure with your domain name registrar. A CNAME makes a domain the alias of another (without redirecting), which is the functionality you're after.
You may need to configure the abc.blog.com website to accept abc.example.com as a valid host (most blogging providers like blogger support this). My blog (via my SO profile) is an example of this.
You'll need to do a proxy redirect:
RewriteEngine On
RewriteRule ^.*$ http://someotherhost.tld/$0 [P]