VPC DNS

Each VPC comes with a built-in DNS resolver (also known as the Amazon-provided DNS server) for several important reasons:

1. Internal DNS Resolution

   • It allows EC2 instances within the VPC to resolve the private DNS hostnames of other instances in the same VPC

   • By default, each EC2 instance gets a private DNS hostname like ip-10-0-0-23.ec2.internal

2. Integration with Route 53

   • The VPC DNS resolver works with Amazon Route 53 Resolver to handle DNS queries

   • It can resolve AWS service endpoints (like S3, RDS, etc.)

   • Supports private hosted zones for your custom domain names within the VPC

3. DNS Resolution Settings

   • The DNS resolver is automatically assigned an IP address at the base of your VPC network range plus 2

   • For example, if your VPC CIDR is 10.0.0.0/16, the DNS server IP would be 10.0.0.2

4. Hybrid Networking

   • Can be configured to resolve DNS queries between your VPC and on-premises networks

   • Supports DNS resolution across VPC peering connections

Key Points to Remember:

• The DNS resolver is free and automatically included with each VPC

• You can't disable it, but you can choose not to use it

• You can configure your own custom DNS servers if needed

• The DNS resolver IP is always the base network address +2 (this is one of those five reserved IPs we discussed earlier)