Route 53 Private Hosted Zone and DNS resolution within VPC

We have the below architecture in AWS, where two EC2 instances can communicate with each other by their private DNS name.

The architecture consist of below components:
1. VPC with two subnets. (one public subnet, another private subnet)
2. Two EC2 instances. (a. primary-ec2 on the public subnet, it has public IP.
b. secondary-ec2 on the private subnet )
3. Route 53 Private Hosted Zone.

You can follow this tutorial to setup the VPC and EC2 instances -

Amazon EC2 with CLI: Deploy EC2 Instance in a Custom VPC

Let’s setup the Private Hosted Zone :

Before you create the Private Hosted Zone, make sure that your VPC has both the DNS hostnames and DNS support options enabled.

Step 1: Go to the AWS Console> Route 53> Hosted Zones.
Step 2: Create a new hosted zone.
Step 3: Provide the domain name and description, choose Private Hosted Zone, select the region where your VPC resides and select the VPC ID.
Step 4: Click on create hosted zone.

Route 53 Private Hosted Zone Configuration

Step 5: Add A records for the EC2 instances.

Get the Private IP of primary-ec2. Provide a Record name, select Record type ‘A’, put the Private IP on the Value, set TTL and select ‘Simple routing’ as the Routing policy.

Similarly add another A record for the secondary-ec2.

Now, it’s time to check.

Log into the primary-ec2 and do nslookup with the secondary-ec2’s private DNS name. You should get the private IP address of the secondary-ec2 as shown below.

Or you can ping the secondary-ec2 by the DNS name (secondary-ec2.demopvtzone.com) from the primary-ec2. (Make sure that you have ICMP protocol enabled in the Security Group Inbound rules of the secondary-ec2)

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Thank you for reading this. Have a great day.

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