Problem with DNS - Pingdom keep sending notification DNS error for my domain

December 24, 2014 5.7k views

before that, here is my digging result

; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> -t NS ocean7cloth.com @ns1.digitalocean.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15104
;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 3
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;ocean7cloth.com.               IN      NS

;; ANSWER SECTION:
ocean7cloth.com.        1800    IN      NS      ns3.digitalocean.com.
ocean7cloth.com.        1800    IN      NS      ns2.digitalocean.com.
ocean7cloth.com.        1800    IN      NS      ns1.digitalocean.com.

;; ADDITIONAL SECTION:
ns1.digitalocean.com.   1800    IN      A       173.245.58.51
ns3.digitalocean.com.   1800    IN      A       198.41.222.173
ns2.digitalocean.com.   1800    IN      A       173.245.59.41

;; Query time: 248 msec
;; SERVER: 173.245.58.51#53(173.245.58.51)
;; WHEN: Wed Dec 24 01:26:45 2014
;; MSG SIZE  rcvd: 148

this is my zone file on DO Dashboard:

$ORIGIN ocean7cloth.com.
$TTL 1800
ocean7cloth.com. IN SOA ns1.digitalocean.com. hostmaster.ocean7cloth.com. 1419384209 10800 3600 604800 1800
ocean7cloth.com. 1800 IN NS ns1.digitalocean.com.
ocean7cloth.com. 1800 IN NS ns2.digitalocean.com.
ocean7cloth.com. 1800 IN NS ns3.digitalocean.com.
ocean7cloth.com. 1800 IN A 128.199.243.196
www.ocean7cloth.com. 1800 IN CNAME ocean7cloth.com.

before i use DNS service from DO, i use Bind9 from tuxlite, but i've uninstalled it for now, and also restart the server (all of them).

i am also got this warning from pingdom tools dns check tool:

ns1.digitalocean.com.

Could not find reverse address for 2400:cb00:2049:1:0:0:adf5:3a33 (3.3.a.3.5.f.d.a.0.0.0.0.0.0.0.0.1.0.0.0.9.4.0.2.0.0.b.c.0.0.4.2.ip6.arpa.).

PTR record(s) for the address could not be found in the .arpa-zone. (ip6.arpa. for IPv6 addresses and in-addr.arpa. for IPv4).
ns2.digitalocean.com.

Could not find reverse address for 2400:cb00:2049:1:0:0:adf5:3b29 (9.2.b.3.5.f.d.a.0.0.0.0.0.0.0.0.1.0.0.0.9.4.0.2.0.0.b.c.0.0.4.2.ip6.arpa.).

PTR record(s) for the address could not be found in the .arpa-zone. (ip6.arpa. for IPv6 addresses and in-addr.arpa. for IPv4).
ns3.digitalocean.com.

Could not find reverse address for 2400:cb00:2049:1:0:0:c629:dead (d.a.e.d.9.2.6.c.0.0.0.0.0.0.0.0.1.0.0.0.9.4.0.2.0.0.b.c.0.0.4.2.ip6.arpa.).

PTR record(s) for the address could not be found in the .arpa-zone. (ip6.arpa. for IPv6 addresses and in-addr.arpa. for IPv4).

is there anyone can explain this? since i'm totally new to develop my own server also the DNS setting

2 Answers

A PTR record is a reverse DNS record that links your server’s IP address with a proper hostname. It is automatically set from the hostname given to the Droplet if the Droplet's name is a Fully Qualified Domain Name [FQDN].

From An Introduction to DNS Terminology, Components, and Concepts:

A fully qualified domain name, often called FQDN, is what we call an absolute domain name. Domains in the DNS system can be given relative to one another, and as such, can be somewhat ambiguous. A FQDN is an absolute name that specifies its location in relation to the absolute root of the domain name system.

This means that it specifies each parent domain including the TLD. A proper FQDN ends with a dot, indicating the root of the DNS hierarchy. An example of a FQDN is "mail.google.com.". Sometimes software that calls for FQDN does not require the ending dot, but the trailing dot is required to conform to ICANN standards.

So you'll want to have your droplet named something like www.ocean7cloth.com

by Justin Ellingwood
DNS, or the Domain Name System, is an integral part of how the internet functions today. However, the way that DNS works is often quite mysterious for new administrators. In this guide, we will discuss some of the common terminology and concepts that are involved in DNS configuration.

Assuming that our private subnet is 10.128.0.0/16, add the reverse zone by with the following lines (note that our reverse zone name starts with "128.10" which is the octet reversal of "10.128"):

zone "128.10.in-addr.arpa" {
type master;
file "/etc/bind/zones/db.10.128"; # 10.128.0.0/16 subnet
allow-transfer { 10.128.20.12; }; # ns2 private IP address - secondary
};

cd /etc/bind/zones
sudo cp ../db.127 ./db.10.128

Edit the reverse zone file that corresponds to the reverse zone(s) defined in named.conf.local:

sudo vi /etc/bind/zones/db.10.128

Initially, it will look something like the following:

$TTL 604800
@ IN SOA localhost. root.localhost. (
1 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
;
@ IN NS localhost. ; delete this line
1.0.0 IN PTR localhost. ; delete this line

In the same manner as the forward zone file, you will want to edit the SOA record and increment the serial value. It should look something like this:

@ IN SOA ns1.nyc2.example.com. admin.nyc2.example.com. (
3 ; Serial

Now delete the two records at the end of the file (after the SOA record). If you're not sure which lines to delete, they are marked with a "delete this line" comment above.

At the end of the file, add your nameserver records with the following lines (replace the names with your own). Note that the second column specifies that these are "NS" records:

; name servers - NS records
IN NS ns1.nyc2.example.com.
IN NS ns2.nyc2.example.com.

Then add PTR records for all of your servers whose IP addresses are on the subnet of the zone file that you are editing. In our example, this includes all of our hosts because they are all on the 10.128.0.0/16 subnet. Note that the first column consists of the last two octets of your servers' private IP addresses in reversed order. Be sure to substitute names and private IP addresses to match your servers:

; PTR Records
11.10 IN PTR ns1.nyc2.example.com. ; 10.128.10.11
12.20 IN PTR ns2.nyc2.example.com. ; 10.128.20.12
101.100 IN PTR host1.nyc2.example.com. ; 10.128.100.101
102.200 IN PTR host2.nyc2.example.com. ; 10.128.200.102

Save and exit the reverse zone file (repeat this section if you need to add more reverse zone files).

Our final example reverse zone file looks like the following:

$TTL 604800
@ IN SOA nyc2.example.com. admin.nyc2.example.com. (
3 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
; name servers
IN NS ns1.nyc2.example.com.
IN NS ns2.nyc2.example.com.

; PTR Records
11.10 IN PTR ns1.nyc2.example.com. ; 10.128.10.11
12.20 IN PTR ns2.nyc2.example.com. ; 10.128.20.12
101.100 IN PTR host1.nyc2.example.com. ; 10.128.100.101
102.200 IN PTR host2.nyc2.example.com. ; 10.128.200.102

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