> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # DNS VPC Demo > This guide explores DNS settings in an AWS VPC and their effects on EC2 instances. In this guide, we’ll explore the two DNS settings available on an AWS Virtual Private Cloud (VPC)—**Enable DNS resolution** and **Enable DNS hostnames**—and demonstrate their effects on EC2 instances. ## Overview of VPC DNS Settings When you create a custom VPC without modifying defaults, the VPC DNS settings look like this (an Internet Gateway is also attached by default): ![The image shows an AWS VPC management console with details of a VPC named "vpcdemo," including its state, CIDR blocks, and associated resources.](https://kodekloud.com/kk-media/image/upload/v1752863194/notes-assets/images/AWS-Networking-Fundamentals-DNS-VPC-Demo/aws-vpc-management-console-vpcdemo.jpg) | Setting | Description | Default | Use Case | | --------------------- | ------------------------------------------------------------------------------------------ | ------- | ---------------------------------------------------------- | | Enable DNS resolution | Allows instances to forward hostname lookups to the Amazon‐provided DNS server (10.0.0.2). | true | Required for any DNS-based name resolution inside the VPC. | | Enable DNS hostnames | Assigns a public DNS hostname to instances that have a public IPv4 address. | false | Useful for mapping public IPs to friendly DNS names. | The Amazon‐provided DNS server is always at the second IP address in the VPC CIDR block (for example, 10.0.0.2 in a 10.0.0.0/16 VPC). *** ## 1. Enable DNS Hostnames By default, **Enable DNS hostnames** is disabled. Launch an EC2 instance in this VPC with these settings: * **AMI**: Amazon Linux 2 * **Instance type**: t2.micro * **Key pair**: your existing key * **Network**: vpcdemo * **Auto-assign Public IP**: Enabled * **Security group**: allow SSH (port 22) and ICMP (All ICMP) from 0.0.0.0/0 Once it’s running, you’ll see only the private DNS name: ![The image shows an AWS EC2 management console with a list of instances, highlighting one instance named "dnsdemo" that is currently running. The details of the selected instance, including its public IPv4 address and instance type, are displayed below.](https://kodekloud.com/kk-media/image/upload/v1752863196/notes-assets/images/AWS-Networking-Fundamentals-DNS-VPC-Demo/aws-ec2-console-dnsdemo-instance-details.jpg) 1. Go to **Actions → Edit VPC settings**. 2. Check **Enable DNS hostnames** and click **Save**. 3. Refresh the EC2 Instances view. The **Public DNS (IPv4)** column is now populated: ```bash theme={null} $ ping ec2-35-173-226-213.compute-1.amazonaws.com PING ec2-35-173-226-213.compute-1.amazonaws.com (35.173.226.213): 56 data bytes 64 bytes from 35.173.226.213: icmp_seq=0 ttl=54 time=35.1 ms ``` *** ## 2. Enable DNS Resolution Next, verify **Enable DNS resolution**. SSH into your instance: ```bash theme={null} $ ssh -i path/to/key.pem ec2-user@35.173.226.213 ``` Return to the VPC console to confirm the CIDR block: ![The image shows an AWS EC2 management console displaying details of a Virtual Private Cloud (VPC) named "vpcdemo," including its ID, state, and CIDR information. The interface includes options for managing subnets, route tables, and other network settings.](https://kodekloud.com/kk-media/image/upload/v1752863197/notes-assets/images/AWS-Networking-Fundamentals-DNS-VPC-Demo/aws-ec2-vpcdemo-management-console.jpg) On the instance, inspect `/etc/resolv.conf`: ```bash theme={null} [ec2-user@ip-10-0-1-144 ~]$ cat /etc/resolv.conf nameserver 10.0.0.2 search ec2.internal ``` Perform a DNS lookup: ```bash theme={null} [ec2-user@ip-10-0-1-144 ~]$ nslookup google.com Server: 10.0.0.2 Address: 10.0.0.2#53 Non-authoritative answer: Name: google.com Address: 142.251.163.100 ``` Because **Enable DNS resolution** is turned on, lookups succeed. To see what happens when you disable it: 1. In the VPC console, choose **Actions → Edit VPC settings**. 2. Uncheck **Enable DNS resolution** and click **Save**. 3. Back on your instance, try: ```bash theme={null} [ec2-user@ip-10-0-1-144 ~]$ nslookup youtube.com ;; connection timed out; no servers could be reached ``` ![The image shows the AWS Management Console with the "Edit VPC settings" page open, displaying options for VPC details, DHCP settings, DNS settings, and network address usage metrics settings.](https://kodekloud.com/kk-media/image/upload/v1752863198/notes-assets/images/AWS-Networking-Fundamentals-DNS-VPC-Demo/aws-management-console-edit-vpc-settings.jpg) With DNS resolution disabled, instances cannot use the Amazon‐provided DNS server. You must configure an alternate DNS server (for example, 8.8.8.8) in your DHCP options or run your own DNS service within the VPC. *** ## References * [AWS VPC Documentation](https://docs.aws.amazon.com/vpc/latest/userguide/what-is-amazon-vpc.html) * [Amazon EC2 User Guide – Networking](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html) * [Route 53 Resolver – Amazon VPC DNS](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resolver.html)