It seems that the Appliance is not capable of reaching another server. How can I verify that the DNS requests are properly working?
An Appliance is relying on the DNS infrastructure for many aspects of the Nexthink Solution. Here is a non-exhaustive list of some of them:
Access to Active Directory servers
Access to the Nexthink Library
Access to the Nexthink Central License Manager (CLM)
Access to the Nexthink Update Repository
Access to other Nexthink Servers
As the underlying system powering the Nexthink Server Components is Linux, you have at your disposal several tools. Here are some ideas on how to troubleshoot issues with DNS queries.
Using "nslookup" command
nslookup is the basic command to quickly get the IP address associated with any fully qualified domain name.
Here is a sample output:
Server: 10.10.10.10 Address: 10.10.10.10#53 Non-authoritative answer: Name: Address: 22.214.171.124
10.10.10.10 is the DNS server that answered my request. Below this information you get the “A Record” (IP Address) of the server behind “library.nexthink.com”.
Using "dig" command
dig has the same purpose as the preceding command but provides a richer output.
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.23.rc1.el6_5.1 <<>> ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14611 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 9, ADDITIONAL: 11 ;; QUESTION SECTION: ;application-library.nexthink.com. IN A ;; ANSWER SECTION: application-library.nexthink.com. 9923 IN A 126.96.36.199 ;; AUTHORITY SECTION: . 69 IN NS ns2142.dns.dyn.com. . 69 IN NS a.ns.zerigo.net. . 69 IN NS d.ns.zerigo.net. . 69 IN NS f.ns.zerigo.net. . 69 IN NS e.ns.zerigo.net. . 69 IN NS b.ns.zerigo.net. . 69 IN NS ns3146.dns.dyn.com. . 69 IN NS ns1195.dns.dyn.com. . 69 IN NS ns4145.dns.dyn.com. ;; ADDITIONAL SECTION: . 12035 IN A 188.8.131.52 . 12035 IN AAAA 2607:fc88:1001:1::4 . 18933 IN A 184.108.40.206 . 18933 IN AAAA 2607:f0d0:1004:82::4 . 5843 IN A 220.127.116.11 . 5843 IN AAAA 2607:fc88:1001:1::4 . 5300 IN A 18.104.22.168 . 5300 IN AAAA 2607:f0d0:3001:90::4 . 34663 IN A 22.214.171.124 . 34663 IN A 126.96.36.199 . 118980 IN A 188.8.131.52 ;; Query time: 1 msec ;; SERVER: 10.10.10.10#53(10.10.10.10) ;; WHEN: Tue Apr 29 09:38:03 2014 ;; MSG SIZE rcvd: 475
The first section starting with “; <<>>” displays a bunch of information like the version number, the global options and other parameters used by dig.
The second section labelled QUESTION displays what was asked to the DNS.
The third section labelled ANSWER is the information the Appliance received from the DNS query.
The fourth section labelled AUTHORITY displays the available name servers for the nexthink.com domain.
The fifth section labelled ADDITIONAL lists the IP addresses of the name servers listed in the preceding section.
The very last section displays stats regarding the query. An important one to look at is the time the query took.