We've picked up a number of issues on mxtoolbox and various other online DNS tools that we have inconsistent glue records. In particular, it appears that the glue records setup at the TLD (.host in this case) has glue records setup for our 4 nameservers but 2 of their NIC servers do not have an IP address assigned.
In particular, .host has 4 NIC servers (a.nic.host - d.nic.host) and it appears that only a.nic.host and b.nic.host has IP addresses assigned to our 4 name servers where c.nic.host and d.nic.host has none.
When we do a query for our domain on pingdom dns check tool we're given a number of errors:
Nameserver ns1.intelli.host is listed for zone intelli.host without address information. Nameserver ns3.intelli.host is listed for zone intelli.host without address information. Nameserver ns4.intelli.host is listed for zone intelli.host without address information.
These errors appear at random (i predict based on which NIC server returned the results).
Ultradns is more precise at the bottom of the trace indicating that online a.nic.host and b.nic.host has IP addresses assigned.
When I however do a:
dig +norec @c.nic.host intelli.host NS
I am given IP addresses for the 4 nameservers - This leads me to believe that either I'm not doing the correct dig command on that the various online tools like pingdom and ultratools are reporting incorrectly (which I doubt)
Can anyone confirm whether my understanding of the issues we experience is correct?
UPDATE (DAY 2)
Thank you all for your help thus far! From answers thus far it appears that it may pingdom leading us in the dark, but I have found 2 other DNS tool sites also giving random results.
What is clear in all of these cases is that, at random, we will get some sort of DNS issue, and from what I can again gather it's when c.nic.host or d.nic.host is reporting glue records:
Note that this one gives different results with some queries. It mostly changes dependant on which server gives it a result (in this case it was d.nic.host):
Nameserver records returned by the parent servers are: ns2.intelli.host. [NO GLUE] [TTL=3600] ns3.intelli.host. [NO GLUE] [TTL=3600] ns1.intelli.host. [NO GLUE] [TTL=3600] ns4.intelli.host. [NO GLUE] [TTL=3600] This information was kindly provided by d.nic.host.
Error also from VIEWDNS: Oops! The IP addresses (GLUE) returned for your nameserver don't match! You should closely observe the nameserver details above and identify where the differences lie.
ULTRADNS https://www.ultratools.com/tools/dnsLookupResult (might have to search here for intelli.host as there is no direct link)
When going to trace, it shows at the bottom the returned HOST records as follows:
host. b.nic.host.66 ms intelli.host. ns2.intelli.host. 188.8.131.52 intelli.host. ns1.intelli.host. 184.108.40.206 intelli.host. ns3.intelli.host. 220.127.116.11 intelli.host. ns4.intelli.host. 18.104.22.168 d.nic.host.3 ms intelli.HOST. ns2.intelli.host. intelli.HOST. ns1.intelli.host. intelli.HOST. ns3.intelli.host. intelli.HOST. ns4.intelli.host. c.nic.host.38 ms intelli.HOST. ns1.intelli.host. intelli.HOST. ns4.intelli.host. intelli.HOST. ns3.intelli.host. intelli.HOST. ns2.intelli.host. a.nic.host.65 ms intelli.host. ns4.intelli.host. 22.214.171.124 intelli.host. ns1.intelli.host. 126.96.36.199 intelli.host. ns2.intelli.host. 188.8.131.52 intelli.host. ns3.intelli.host. 184.108.40.206