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

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