Failover IP Reverse DNS

[LotsOfQ]

I've bought a failover ip and I've added to and everything is working fine but problem adding reverse dns. I've tried to add rdns.mydomain.com for reverse dns with my hosting and it keep getting error. "Cannot resolve NS query."

What do I need to do?

[MRatWork]

Add 'a record' for 'rdns' in your 'mydomain.com' dns setting in panel.

[LotsOfQ]

I added rdns to a record as you said but it didn't work. However if I use ns1.mydomain.com then it works. Am I doing something wrong?

Hostname
rdns

Value
my failover ip address

Is that right?

[MRatWork]

Inform here 'sh /script/sysinfo'.

[LotsOfQ]

A. Control Panel:
   - Kloxo-MR: 7.0.0.b-2016090305
   - Web: hiawatha-10.3.0-f.1.mr.el6.x86_64
   - PHP: php54s-5.4.45-1.ius.el6 (fpm mode)
B. Plateform:
   - OS: CentOS release 6.8 (Final) x86_64
   - Hostname: server.mydomain.com
C. Services:
   1. MySQL: MariaDB-server-10.0.27-1.el6.x86_64
   2. PHP:
      - Installed:
        - Branch: php54-cli-5.4.45-1.ius.el6.x86_64
        - Multiple:
          * php52m-5.2.17-102.mr.el6
          * php53m-5.3.29-1.ius.el6
          * php54m-5.4.45-1.ius.el6
          * php55m-5.5.38-1.ius.el6
          * php56m-5.6.25-1.ius.el6
          * php70m-7.0.10-1.w6
      - Used: php54m-fpm
      - Multiple: enable
   3. Web Used: nginxproxy
     - Hiawatha: hiawatha-10.3.0-f.1.mr.el6.x86_64
     - Lighttpd: lighttpd-1.4.41-1.el6.x86_64
     - Nginx: nginx-1.11.3-1.el6.ngx.x86_64
     - Apache: httpd24u-2.4.23-2.ius.el6.x86_64
       - PHP Type: php-fpm_event
       - Secondary PHP: on
   4. WebCache: none
     - ATS: --uninstalled--
     - Squid: --uninstalled--
     - Varnish: --uninstalled--
   5. Dns: nsd
     - Bind: --uninstalled--
     - DJBDns: --uninstalled--
     - NSD: nsd-4.1.11-1.el6.x86_64
     - PowerDNS: --uninstalled--
     - Yadifa: --uninstalled--
   6. Mail: qmail-toaster-1.03-1.3.55.mr.el6.x86_64
      - pop3/imap4: courier-imap-toaster-4.1.2-1.3.20.mr.el6.x86_64
      - smtp: qmail-toaster-1.03-1.3.55.mr.el6.x86_64
      - spam: package none is not installed
   7. Stats: awstats
D. Memory:
                total       used       free     shared    buffers     cached
   Mem:         11626       1178      10447         88         76        528
   -/+ buffers/cache:        573      11052
   Swap:            0          0          0
E. Disk Space:
   Filesystem      Size  Used Avail Use% Mounted on
   /dev/vda1        50G   18G   29G  38% /

[MRatWork]

Using 'ns1.mydomain.com' is work because exists in dns setting and already propagation. If using 'rdns.mydomain.com', need add 'a record' in dns setting and wait a couple of hours till propagation completed.

[LotsOfQ]

Yes, you're right. It works now. Thank you so much.