Reverse DNS (rDNS) is the method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses.
Setting up reverse DNS for your domain can help ensure email delivery to mail servers which perform simple anti-spam measures which as a three-way handshake to determine that the forward DNS matches the reverse DNS which matches the fully qualified domain name (FQDN) of the email header.
This tutorial will guide you through setting up reverse DNS in DNS Made Easy. The basic steps are as follows:
- Contact your IP provider to request delegation of your reverse DNS to DNS Made Easy name servers where you are provided with your reverse DNS domain.
- Create your reverse DNS domain in DNS Made Easy.
STEP #1: GET YOUR REVERSE DNS DELEGATED TO DNS MADE EASY
First we obtain the IP address of the server we are setting up reverse DNS for:
$ host mx2.dnsmadeeasy.com
mx2.dnsmadeeasy.com has address 126.96.36.199
You will need to find out who owns your IP block (usually this is your ISP or hosting provider). NOTE:You can determine the owner of an IP address by performing a WHOIS search on the IP in question on ARIN’s website.
This provider will need to delegate your IP block to the DNS Made Easy name servers for reverse DNS resolution. This is similar to how you delegate your domain to the DNS Made Easy name servers by informing you registrar you are using our name servers. Usually an ISP or hosting company will only delegate the reverse DNS if you have 256 IPs (a full class C) or more, but some companies have been known to make an exception. If your provider will not delegate the reverse DNS to DNS Made Easy then there is no reason to continue this tutorial. You can request they set up the reverse DNS for you and they will host your PTR records.
Once your ISP or hosting company has agreed that they will assign the reverse DNS to DNS Made Easy ask them for the reverse zone name that you need to create within DNS Made Easy. This is a special reverse DNS domain that ends in “in-addr.arpa”. The zone (domain) “1.168.192.in-addr.arpa” would actually be the reverse DNS for the 192.168.1 class C. So this would handle the reverse DNS for IPs 192.168.1.1 to 192.168.1.256.
If your IP block is smaller than a class C then your zone (domain) might look like this “0/188.8.131.52.in-addr.arpa” or “0-184.108.40.206.in-addr.arpa”. The difference being only syntax, however you must create your domain within DNS Made Easy using the exact same syntax your ISP or hosting provider used to delegate it. The zones above would be the zone that would handle 128 IPs. This would be the zone for the IPs 192.168.1.1 to 192.168.1.128.
Double check your delegation syntax with Reverse DNS Trace which a free tool provided by DNS Made Easy Tech Support. Please note, DNS Made Easy’s delegation is already performed in this screen shot.
DNS Made Easy’s IP block is a full class C so the syntax of our delegation is 147.94.208.in-addr.arpa. This is the domain we create, this domain is defined within the DNS Made Easy and assigned to ns0-ns4.dnsmadeeasy.com, thus those are the name servers the delegation was performed to. If your reverse DNS domain is not configured within DNS Made Easy yet, the name servers you provide for delegation may be different.
STEP #2: CREATE YOUR REVERSE DNS DOMAIN IN DNS MADE EASY
- Select the DNS Menu
- Select Managed DNS
- Click on “Add Domains” to add a new domain
- The delegation is 147.94.208.in-addr.arpa, so this is the domain we create. It is assigned to ns0-ns4.dnsmadeeasy.com which is the same group of name servers our Reverse DNS Trace delegation shows.
- After you have added your reverse DNS domain into the DNS Made Easy system you are provided with a list of name servers that your reverse zone is assigned. These must match the DNS Made Easy name servers that you requested delegation to in Step 1. Below is a screen shot of the assigned name servers to the domain 147.94.208.in-addr.arpa.
STEP #3: CREATE YOUR PTR RECORDS IN YOUR REVERSE DNS DOMAIN
You will now create PTR records within your reverse DNS domain that was just added into our system. Pointer records are used to map a network interface (IP) to a host name. These are primarily used for reverse DNS. PTR records should be created for hosts as needed. Please note that the data/value field of each PTR record must conclude with a dot (.). This will keep your domain name from being appended to the end of your configuration.
We define a PTR record for mx2.dnsmadeeasy.com. The name of the record is 129, the last octet of the IP address. The data is the host name of the server followed by a trailing dot(.).