Question : How do resolve a Port 80 error using the public IP address of a website vs. the FQDN?

I am running a pre-deployment verification .exe for a software product I am about to upgrade.  The .exe runs serveral tests to check/verify OS, Memory, CPU, DNS, IIS, WWW, DNS Lookup, HTTP Port, SSL Port, and SSL Certificate.  All tests pass except for the HTTP Port. I receive this from the report:

Port 80 on host unreachable from the internet: System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 24.249.176.211:80 at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) at System.Net.Sockets.Socket.Connect(EndPoint remoteEP) at CheckServerHandler.TestPort(IPHostEntry entry, Int32 port, TESTRESULT& result, String& reason)

I can get to the "Under Construction" page using the http://domainname.com:80 , but when the test uses the ip address and port 80 it fails.  This may be basic 101 stuff.  Hope you can help.

Answer : How do resolve a Port 80 error using the public IP address of a website vs. the FQDN?

I guess I assumed that if ur using http://domianname and it works then port 80 is forwarded but this might no be the case and its resolving internally only.  Yes the firewall may be blockign port 80 externally.