These domains are not returning on digs for any IP records on the nameservers they have set:
Code:
# dig @ns1.gengbiz.com allhostone.co.uk
dig: couldn't get address for 'ns1.gengbiz.com': failure
This is just one example. While the nameservers do show registration at internic (Home and Home) with the IPs for these nameservers pinging, the domains themselves do not show DNS zones when trying to query them for digs.
This would appear to be an issue with the server for the DNS zone setup or the bind/named service. At this point due to the inability to tell what is causing it without access to the machine, please open up a ticket in WHM > Support Center > Contact cPanel or using the link in my signature for us to investigate.