DNS

There’s a dusty shelf in every network closet where good intentions go to die. Or worse, to gossip. You centralize DNS for simplicity. You enable logging for accountability. You peer VPCs for convenience. A few sprints later, your DNS logs have become that chatty neighbor who sees every car that comes and goes, remembers every visitor, and pieces together a startlingly accurate picture of your life.

They aren’t leaking passwords or secret keys. They’re leaking something just as valuable: the blueprints of your digital house.

This post walks through a common pattern that quietly spills sensitive clues through AWS Route 53 Resolver query logging. We’ll skip the dry jargon and focus on the story. You’ll leave with a clear understanding of the problem, a checklist to investigate your own setup, and a handful of small, boring changes that buy you a lot of peace.

The usual suspects are a disaster recipe in three easy steps

This problem rarely stems from one catastrophic mistake. It’s more like three perfectly reasonable decisions that meet for lunch and end up burning down the restaurant. Let’s meet the culprits.

1. The pragmatic architect

In a brilliant move of pure common sense, this hero centralizes DNS resolution into a single, shared network VPC. “One resolver to rule them all,” they think. It simplifies configuration, reduces operational overhead, and makes life easier for everyone. On paper, it’s a flawless idea.

2. The visibility aficionado

Driven by the noble quest for observability, this character enables Route 53 query logging on that shiny new central resolver. “What gets measured, gets managed,” they wisely quote. To be extra helpful, they associate this logging configuration with every single VPC that peers with the network VPC. After all, data is power. Another flawless idea.

3. The easy-going permissions manager

The logs have to land somewhere, usually a CloudWatch Log Group or an S3 bucket. Our third protagonist, needing to empower their SRE and Ops teams, grants them broad read access to this destination. “They need it to debug things,” is the rationale. “They’re the good guys.” A third, utterly flawless idea.

Separately, these are textbook examples of good cloud architecture. Together, they’ve just created the perfect surveillance machine: a centralized, all-seeing eye that diligently writes down every secret whisper and then leaves the diary on the coffee table for anyone to read.

So what is actually being spilled

The real damage comes from the metadata. DNS queries are the internal monologue of your applications, and your logs are capturing every single thought. A curious employee, a disgruntled contractor, or even an automated script can sift through these logs and learn things like:

Service Hostnames that tell a story: Names like billing-api.prod.internal or customer-data-primary-db.restricted.internal do more than just resolve to an IP. They reveal your service names, their environments, and even their importance.
Secret project names: That new initiative you haven’t announced yet? If its services are making DNS queries like project-phoenix-auth-service.dev.internal, the secret’s already out.
Architectural hints: Hostnames often contain roles like etl-worker-3.prod, admin-gateway.staging, or sre-jumpbox.ops.internal. These are the labels on your architectural diagrams, printed in plain text.
Cross-Environment chatter: The most dangerous leak of all. When a query from a dev VPC successfully resolves a hostname in the prod environment (e.g., prod-database.internal), you’ve just confirmed a path between them exists. That’s a security finding waiting to happen.

Individually, these are harmless breadcrumbs. But when you have millions of them, anyone can connect the dots and draw a complete, and frankly embarrassing, map of your entire infrastructure.

Put on your detective coat and investigate your own house

Feeling a little paranoid? Good. Let’s channel that energy into a quick investigation. You don’t need a magnifying glass, just your AWS command line.

Step 1 Find the secret diaries

First, we need to find out where these confessions are being stored. This command asks AWS to list all your Route 53 query logging configurations. It’s the equivalent of asking, “Where are all the diaries kept?”

aws route53resolver list-resolver-query-log-configs \
--query 'ResolverQueryLogConfigs[].{Name:Name, Id:Id, DestinationArn:DestinationArn, VpcCount:ResolverQueryLogConfigAssociationCount}'

Take note of the DestinationArn for any configs with a high VpcCount. Those are your prime suspects. That ARN is the scene of the crime.

Step 2 Check who has the keys

Now that you know where the logs are, the million-dollar question is: who can read them?

If the destination is a CloudWatch Log Group, examine its resource-based policy and also review the IAM policies associated with your user roles. Are there wildcard permissions like logs:Get* or logs:* attached to broad groups?

If it’s an S3 bucket, check the bucket policy. Does it look something like this?

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::123456789012:root"
      },
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::central-network-dns-logs/*"
    }
  ]
}

This policy generously gives every single IAM user and role in the account access to read all the logs. It’s the digital equivalent of leaving your front door wide open.

Step 3 Listen for the juicy gossip

Finally, let’s peek inside the logs themselves. Using CloudWatch Log Insights, you can run a query to find out if your non-production environments are gossiping about your production environment.

fields @timestamp, @message
| filter @message like /\.prod\.internal/
| filter vpc.id not like /vpc-prod-environment-id/
| stats count(*) by vpc.id as sourceVpc
| sort by @timestamp desc

This query looks for any log entries that mention your production domain (.prod.internal) but did not originate from a production VPC. Any results here are a flashing red light, indicating that your environments are not as isolated as you thought.

The fix is housekeeping, not heroics

The good news is that you don’t need to re-architect your entire network. The solution isn’t some heroic, complex project. It’s just boring, sensible housekeeping.

Be granular with your logging: Don’t use a single, central log destination for every VPC. Create separate logging configurations for different environments (prod, staging, dev). Send production logs to a highly restricted location and development logs to a more accessible one.
Practice a little scrutiny: Just because a resolver is shared doesn’t mean its logs have to be. Associate your logging configurations only with the specific VPCs that absolutely need it.
Embrace the principle of least privilege: Your IAM and S3 bucket policies should be strict. Access to production DNS logs should be an exception, not the rule, requiring a specific IAM role that is audited and temporary.

That’s it. No drama, no massive refactor. Just a few small tweaks to turn your chatty neighbor back into a silent, useful tool. Because at the end of the day, the best secret-keeper is the one who never heard the secret in the first place.

Your browser instantly connects you to your desired website when you type in its address and hit enter. It’s a seamless experience we often take for granted. But behind this seemingly simple action lies a complex system that makes it all possible: the Domain Name System (DNS). Think of DNS as the internet’s global directory, translating human-readable domain names into the numerical IP addresses that computers use to communicate. And when managing DNS with reliability and scalability, AWS Route 53 takes center stage. Route 53 is Amazon’s highly available and scalable DNS service, designed to route traffic to your application’s resources with remarkable precision and minimal latency. In this guide, we’ll demystify the most common DNS record types and show you how to use them effectively with Route 53, using practical examples.

Let’s jump into DNS records by breaking them down into simple, relatable examples and exploring real-world use cases. We’ll see how they work together, like a well-orchestrated symphony, to make the internet navigable.

The basics of DNS Records

DNS records are like traffic signs for the internet, directing users to the right destinations. But instead of physical signs, they’re digital entries that guide web browsers and other services. Route 53 makes managing these records straightforward. Here are the most common types:

A Record (Address Record)

Think of an A Record as the street address for your website. It maps a domain name (e.g., example.com) to an IPv4 address (e.g., 192.0.2.1). It’s the most basic thing. It just tells the internet where your website lives.

Purpose: Directs traffic to web servers or other IPv4 resources.
Analogy: Imagine telling a friend to visit you at your home address, that’s what an A Record does for websites. It’s like saying, “Hey, if you’re looking for example.com, it’s over at this IP address.”
Use Case: Hosting a website like example.com on an EC2 instance or an on-premises server.

CNAME Record (Canonical Name)

A CNAME Record is like a nickname for your domain. It maps an alias domain name (e.g., www.example.com) to another “canonical” domain name (e.g., example.com).

Purpose: Simplifies management by allowing multiple domains to point to the same resource. It’s like having various roads leading to the same destination.
Analogy: It’s like calling your friend “Bob” instead of “Robert.” Both names point to the same person.
Use case: Scaling applications by mapping api.example.com to an Application Load Balancer’s DNS name, such as app-load-balancer-456.amazonaws.com. You point your CNAME to the load balancer, and the load balancer handles distributing traffic to your servers.

AAAA Record (Quad A Record)

For the modern internet, AAAA Records map domain names to IPv6 addresses (e.g., 2001:db8::1).

Purpose: Ensures compatibility with IPv6 resources, which is becoming increasingly important as the internet grows.
Analogy: Think of this as an upgrade to a new address system for the internet, ready for the future. It’s like moving from a local phone system to a global one.
Use case: Enabling access to your website via IPv6. This ensures your site is reachable by devices using the newer IPv6 standard.

MX Record (Mail Exchange)

MX Records ensure emails sent to your domain arrive at the correct mail server.

Purpose: Routes emails to the appropriate mail server.
Analogy: Like sorting mail at a post office to send it to the right address. Each piece of mail (email) needs to be directed to the correct recipient (mail server).
Use case: Configuring email for domains with Google Workspace or Microsoft 365. This ensures your emails are handled by the right service.

NS Record (Name Server)

NS Records delegate a domain or subdomain to specific name servers.

Purpose: Specifies which servers are authoritative for answering DNS queries for a domain. In other words, they know all the A records, CNAME records, etc., for that domain.
Analogy: It’s like asking a specific guide for directions within a city. That guide knows the specific area inside and out.
Use case: Delegating subdomains like dev.example.com to a different DNS provider, perhaps for testing purposes.

TXT Record (Text Record)

TXT Records store arbitrary text data, often used for domain verification or email security configurations (e.g., SPF, DKIM).

Purpose: Provides information to external systems.
Analogy: Think of it as posting a sign with instructions outside your door. This sign might say, “To verify you own this house, please show this specific code.”
Use case: Adding SPF, DKIM, and DMARC records to prevent email spoofing and improve email deliverability. This helps ensure your emails don’t end up in spam folders.

Alias Record

Exclusive to AWS, Alias Records map domain names to AWS resources like S3 buckets or CloudFront distributions without needing an IP address.

Purpose: Reduces costs and simplifies DNS management, especially within the AWS ecosystem.
Analogy: A direct shortcut to AWS resources without the extra steps. Think of it as a secret tunnel directly to your destination, bypassing traffic.
Use case: Mapping example.com to a CloudFront distribution for CDN integration. This allows for faster content delivery to users around the world. Or, say you have a static website hosted on S3. An Alias record can point your domain directly to the S3 bucket, without needing a separate web server.

Putting it all together

Let’s look at how these records work in harmony to power your website. See? It’s not so complicated when you break it down. Each record has its job, and they all work together like a well-oiled machine.

Hosting a scalable website

Register your domain: Let’s say you register example.com using Route 53.
Create an A Record: You map example.com to an EC2 instance’s IP address where your website is hosted.
Add a CNAME Record: For www.example.com, you create a CNAME pointing to example.com. This way, both addresses lead to your site.
Utilize Alias Records: To speed up content delivery, you create an Alias record connecting example.com to a CloudFront distribution. This caches your website content at edge locations closer to your users. And shall we use another Alias Record to connect static.example.com to an S3 bucket, to serve your images faster? Why not.
Implement TXT Records: You add TXT records for email authentication (SPF, DKIM) to ensure your emails are trusted and delivered reliably.
Enable health checks: Route 53 can automatically monitor the health of your EC2 instances and route traffic away from unhealthy ones, ensuring your site stays up even if a server has issues. Route 53 can even automatically remove unhealthy instances from your DNS records.

This setup ensures high availability, scalability, and secure communication. But what makes Route 53 special? It’s not just about creating these records; it’s about doing it reliably and efficiently. Route 53 is designed for high availability and low latency. It uses a global network of DNS servers to ensure your website is always reachable, even if one server or region has problems. That means faster loading times for your users, no matter where they are.

Closing thoughts

AWS Route 53 isn’t just about creating DNS records, it’s about building robust, scalable, and secure internet infrastructure. It’s about making sure your website is always available to your users, no matter what. It’s like having a team of incredibly efficient digital postal workers who know exactly how to deliver each data packet to its correct destination. And what’s fascinating is that, like a well-designed metro system, Route 53 operates on multiple levels: it can direct traffic based on latency, geolocation, or even the health status of your services. Consider for a moment the massive scale at which services like Netflix or Amazon operate, keeping their platforms running smoothly with millions of simultaneous users. Part of that magic happens thanks to services like Route 53.
The beauty of it all lies in its apparent simplicity for the end user, everything works seamlessly, but behind the scenes, there’s a complex orchestration of systems working in perfect harmony. It’s like a symphony where each DNS record is a different instrument, and Route 53 is the conductor ensuring everything sounds exactly as it should.

What your DNS logs are saying behind your back

The usual suspects are a disaster recipe in three easy steps

So what is actually being spilled

Put on your detective coat and investigate your own house

The fix is housekeeping, not heroics

Practical guide to DNS Records in AWS Route 53