Error: Unable to Resolve Host Name (or DNS Name)

Problem Summary:


Customer reports that when attempting to connect to a controller via Ethernet Port, they receive an error message that the software is unable to resolve a host or DNS name.




There are three likely causes for this type of error:


  1. Improper PC Access Configuration
  2. Anti-Virus and/or Spyware Software
  3. DDNS Service Problem




  1. Improper PC Access Configuration – this is a common problem among new and inexperienced PC Access users. When entering in the DDNS name under Configure>>Network, the user will mistakenly enter in something like  TTP:// PC Access does not expect to see the HTTP protocol specified, and therefore does not know to remove it before asking Windows to resolve the address. Removing the HTTP:// from the address should resolve this problem.
  2. Anti-Virus and Spyware – although rare, it is possible that these types of software can be the culprit. Some software keeps track of program checksums. Occasionally when software is updated, and this checksum changes, the security
    applications mistakenly flag the application as altered and possibly infected. This can result in the program not running at all, or limiting access to some features like Ethernet connections. If you suspect this may be the problem, you
    can view the Log to see if there is any PC Access recognition. If found, you can contact the vendor for information on removing such restrictions.
  3. DDNS Service Problem - PC Access calls the Windows address resolution mechanism when a DNS name is used in place of an IP Address. If Windows can resolve a DNS name, then PC Access should work. A quick and easy test is the Ping command (if supported by the DDNS service). If Windows is unable to resolve the name, then the problem resides within the DDNS service itself.