Unfortunately the standard DNS A-record (domain name to IP address)
used by web-browsers to locate web-servers does not include a port
number. Web-browsers use the URL protocol prefix (http://) to
determine the port number (http = 80, https = 443, ftp = 21, etc.)
unless the port number is specifically typed in the URL (for example
“http://www.simpledns.com:5000” = port 5000).
Can I specify a TCP/IP port number for my web-server in DNS? (Other than the standard port 80)