I am having a problem accessing this website from inside the company's network.
I am able to access other websites in my company from inside the company's network. I am also able to access the above-mentioned website if I am at a different location other than inside my company. Can I find out if the problem lies with my Cisco router?
Without more detailed information about your network its not possible to give a guaranteed correct answer, but it is quite probable the problem is as follows:
Your local Network is probably behind NAT (If your IP address starts with 192.168, 10.x or 172.[16-31].x and you can use the Internet you are behind NAT).
Your server is on the same network as your computers (ie its IP address is in one of the ranges above). Your [Cisco] router has got some logic that whenever an address comes to it on port 80 of its external IP address is redirects the request to the web server.
The address advertised in DNS is actually the external address of the Cisco router.
When you are on your local network, the Cisco router can not redirect the external address to the internal address, so it does not work for you.
[ If this is the case, you can test it by adding the domain name for the server and the servers internal IP address to your hosts file, which will solve the problem for your computer. You could then either modify the DNS your office uses to provide a different answer for computers on your network or add this value to the hosts files on all the computers - or you can modify your network so that your server is on a separate physical network or a "real" IP address.]
