My domain on GoDaddy is set up with DNS forwarding to the Heroku app - this works fine from all of the internet connections I've tried except for the one at work. How can I troubleshoot this issue? Is it a case of ports being blocked? Why might that matter?
I do believe that this sounds a lot like one of two problems. This solution does assume that you have recently setup the domain forwarding, such as in the last 24 - 72 hours. If this is the case then the solution may also find itself since it could be just a longer then normal delay on the propagation of the domain changes.
The DNS server that is used from the corporate network has not been updated with the correct address to point your domain to. Sometimes some DNS servers take a bit of time before they become aware of a record change. This is one reason why when your are setting up your IP address for your systems it allows for a primary and secondary DNS server IP.
The DNS cache that is maintained on some network gateways and or systems may need to be updated or flushed. This process can be a bit equipment specific depending on what equipment is access permissions are involved.