Unable to resolve the hostname to an IP address.
When the TCP address is checked by our servers, we wait a standard 15 seconds for the DNS Server to respond with an IP. If we do not detect a response, this error will be triggered.
TCP (Transmission Control Protocol) is a specific way to transmit and format data over a network between two IP addresses, hence TCP/IP. Most web traffic uses the TCP protocol, including email and other protocols, such as HTTP, HTTPS, SMTP, POP3, IMAP, SSH,and FTP.
The requested TCP hostname goes out to a DNS server and gets converted into an IP address.
Double check the TCP address, including the port
Try running a DNS Lookup on your domain to see if there are any issues with your DNS servers
If you are a paid member of MxToolbox, you can view the history and performance data of a monitor you’ve set up to pinpoint when this problem started occurring
One of the best ways to get help if you are a MxToolbox paid member is to create a support ticket, and one of our staff will be happy to assist you