Understanding CNAME and Alias Records in Amazon Route 53

When setting up a website or web service, you may come across terms like CNAME and Alias records in Amazon Route 53. Both are used to direct traffic to the correct server, but they work in slightly different ways. Let’s break it down in simple terms.

What is a CNAME Record?

A CNAME (Canonical Name) record points one domain to another domain. It’s like saying, "If someone goes to blog.example.com, send them to example.com."

For example:

• You want www.example.com to go to example.com.

• You create a CNAME record that says www.example.com points to example.com.

CNAME records can only point to other domain names, not directly to IP addresses.

What is an Alias Record?

An Alias record is similar to a CNAME, but it’s specific to Amazon Route 53. It’s used to map a domain to AWS services like an S3 bucket or a CloudFront distribution. Unlike a CNAME, an Alias record can point directly to resources like load balancers or the root domain (like example.com).

Alias records have some advantages:

• They can point to AWS services.

• They support the root domain (example.com), which CNAMEs can’t do.

When to Use CNAME vs. Alias in Route 53?

• Use CNAME when you want to redirect one domain to another, especially for subdomains like www.example.com.

• Use Alias when working with AWS resources or when you need to point a root domain (like example.com) to an AWS service like a load balancer or S3.

Key Differences

• CNAME can’t be used for root domains (like example.com); it only works for subdomains.

• Alias can be used for both root domains and subdomains and is optimized for AWS services.

In conclusion, if you're using AWS resources, Alias records are the better option within Route 53. For simple domain redirection to other domains, CNAME records are a good choice.