I am using Amazon Route 53 and want to set up reverse domain name service (DNS) resolution for my on-premises SMTP server. How can I do this?
If you use non-AWS resources, your IP addresses might belong to a third party, such as another cloud computing platform or your internet service provider (ISP). In this case, you must use the method provided by the owner of the IP addresses to configure reverse DNS. Sometimes, the owner of the IP addresses requires you to create a reverse DNS record and provide only your name servers to them for delegation. You can configure Route 53 to respond to reverse DNS lookup queries for your server by creating a public hosted zone and putting a PTR record there.
Note: If you use AWS-provided Elastic IP addresses for your servers, create a forward DNS record (record type A) that points to the correct Elastic IP address. Then, complete the Request to Remove Email Sending Limitations form. Be sure to specify each domain name for your servers and the corresponding Elastic IP address.
Note: This resolution uses the following example IP addresses for the SMTP server: 22.214.171.124 (IPv4) and 2000:1234:5678:9012:3456:7890:1234:5678 (IPv6).
Create a public hosted zone
Follow the steps in Creating a Public Hosted Zone to create a public hosted zone for your server’s IP address. For example, 3.2.1.in-addr.arpa (IPv4) or 126.96.36.199.188.8.131.52.184.108.40.206.0.0.0.2.ip6.arpa (IPv6).
Create a record set and add a PTR record
Follow the steps in Creating Records by Using the Amazon Route 53 Console to create a record set for your hosted zone. Then, add a PTR record for your SMTP server.
For Name, enter the reversed IP address plus in-addr.arpa (IPv4) or ip6.arpa (IPv6). For example, 220.127.116.11.in-addr.arpa (IPv4) or 18.104.22.168.22.214.171.124.0.9.8.7.126.96.36.199.188.8.131.52.184.108.40.206.220.127.116.11.0.0.0.2.ip6.arpa (IPv6).
For Type, select PTR – Pointer.
For Value, enter the fully qualified domain name (FQDN) of the SMTP server. For example, mail.example.com.
Note: If your domain has multiple IP blocks, you must create additional reverse hosted zones with corresponding PTR records to resolve the IP addresses.
Set up delegation
After you create the PTR record, you must ask the owner of the IP addresses to set up delegation to the name servers in your reverse hosted zone. To locate name server details:
- Sign in to the Route 53 console.
- In the navigation pane, choose Hosted zones.
- Select the hosted zone that you set up.
- Select the record whose Type is NS.
- Note the record’s Value.
Note: The time for this new configuration to take effect depends on the time to live (TTL) records of the previous NS record, which might be cached in end-user local DNS servers.