This can be caused by a few different issues.
* View domain names config. If the host they're querying for does not have a "global" record, this could be the cause.
* Unable to get any results from our name servers. For this we need a traceroute from the customer
Ask customer to run DNSTool http://opennms.dnsbycomodo.net/DNSTool/ ... they must copy and paste results back to support
Run the following commands and send them back to us:
in windows traceroute is 'tracert'
[windows and some macs]
[type] server ns1.dnsbycomodo.net
[type] server ns2.dnsbycomodo.net
[linux and some macs]
dig @ns1.dnsbycomodo.net _x.dnsbycomodo.net
dig @ns2.dnsbycomodo.net _x.dnsbycomodo.net
Copy and paste all results back to support and escalate.