This situation could be a little tricky. If you have seen it before its a fix, otherwise, it might take a couple of days to troubleshoot.
Issue:
Internal domain mycompany.com matches the external url mycompany.com. Internal DNS server is unable to resolve the name
Solution:
First in order for mycompany.com to redirect to www.mycompany.com in a web browser, we need to add a host (A) record at your DNS provider like GoDaddy.
x.x.x.x would be the public IP of your website.
In the case where the internal Forward Lookup zone is the same as the website URL we need to add an internal DNS record
This is usually done by adding a record for WWW and pointing to the public IP address of the website.
In the rare cases where your external website does not automatically redirect mycompany.com to www.mycompany.com, you will the above-mentioned solution will not work.
To resolve this issue, we need to set up a blank DNS A record
