This article details how to test Authoritative DNS Resolution with an external tool.
1. Browse to http://www.digwebinterface.com
2. Enter the list of hosts you wish to test under Hostnames or IP addresses:
3. Select Specify myself: under Nameservers and enter the UltraDNS name servers you wish to test (usually the ones that were assigned to you by Customer Support)
4. Click Dig
Insight into Step 4
The answers should match whatever you have configured for the host in question in https://portal.ultradns.com