Quote Originally Posted by praveen221288 View Post
Hi,, I tried to ping the IP addresses 173.194.41.68 through 173.194.41.78 but it shows " connect: Network is unreachable ", I also tried with DNS servers by http://www.opendns.com/, still problem persist.
Your problem is larger than just with your DNS server then. You said before "I already have internet connection, I am able to surfing well in my browser" but it appears you don't have any connectivity to the part of Internet where dl.google.com is located. It's very difficult to give specific advice with this. It sounds as though the problem may not be with your machine but with the network to which you are connected. Can other machines on the same network as your machine reach dl.google.com? Do the people who run your network think you should be able to reach dl.google.com? Is your networking set up using DHCP or are you manually entering IP address, subnet, etc? If the latter, are you sure you're entered everything correctly?