How to: Check DNS Status of a Domain
====================================

In the process of administering an InterWorx server, it may be necessary to
occasionally check the status of a DNS record, either against the server or other DNS
servers. There are many websites that offer the ability to check DNS
propagation, to examples being `IntoDNS <http://intodns.com>`__ and `WhatsMyDNS
<https://www.whatsmydns.net/>`__. However, very few
services offer the wide range of options available in the ``dig`` command.

Using the ``dig`` command provides administrators with a powerful tool to check
and confirm DNS records for their domains. More complete documentation can be
found here: `<https://linux.die.net/man/1/dig>`__ or by running ``man dig`` on a
Linux server. Below are a few examples of how to check DNS records with
``dig``.

In the case where a public DNS record does not match the expected address of
the record, it may be helpful to check the DNS against the InterWorx server to
determine if it is showing the correct information.

.. contents::

Using ``dig`` to Check DNS Records
----------------------------------

Most commands follow the format below, where ``type`` is the type of record to check (A, AAAA, CNAME, TXT, etc.),
``domain`` is the domain name to check, and ``server`` is the DNS server to check
against:

.. code-block::

   dig type domain @server

The following examples use interworx.com as the ``domain``.   

* To check interworx.com's A record using upstream DNS servers:

   .. code-block::

      [root@iw7 ~]# dig a interworx.com +short
      3.222.247.74
      54.166.117.4
      34.232.198.112

* To check interworx.com's A record using a specific DNS server.  In this example, "ns1.interworx.com" is the domain of a 
  specific nameserver. Replace this with the domain/IP address of the nameserver to check:

   .. code-block::

      [root@iw7 ~]# dig a interworx.com +short @ns1.interworx.com
      10.1.14.83

* If more verbose output is desired, removing ``+short`` will provide a more
  full list of the record:

   .. code-block::

      [root@iw7 ~]# dig a interworx.com

      ; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.3 <<>> a interworx.com
      ;; global options: +cmd
      ;; Got answer:
      ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54687
      ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

      ;; OPT PSEUDOSECTION:
      ; EDNS: version: 0, flags:; udp: 512
      ;; QUESTION SECTION:
      ;interworx.com.			IN	A

      ;; ANSWER SECTION:
      interworx.com.		59	IN	A	34.232.198.112
      interworx.com.		59	IN	A	54.166.117.4
      interworx.com.		59	IN	A	3.222.247.74

      ;; Query time: 18 msec
      ;; SERVER: 8.8.8.8#53(8.8.8.8)
      ;; WHEN: Sun Feb 28 13:50:54 EST 2021
      ;; MSG SIZE  rcvd: 88