CNAME , Alias & Domain Apex | Overview & Hands-On.

CNAME,  Alias &  Domain Apex - Overview & Hands-On.

In Amazon Route 53, both CNAME and Alias records are used to map one domain name to another, but they behave differently and are used in different scenarios.

 CNAME vs Alias – Key Differences

Feature	CNAME Record	Alias Record (Route 53-specific)
Purpose	Maps one domain name to another	Maps a domain to AWS resources (like ELB, S3, CloudFront)
Standard DNS	Yes – part of standard DNS specification	No – Route 53–specific feature
Zone Apex Allowed?	❌ Not allowed at root (e.g., twtechapp.com)	✅ Allowed at root domain
Supported by Route 53?	✅ Yes	✅ Yes
DNS Query Charges	✅ Yes	❌ No (free for AWS targets)
Target Types	Any domain name	AWS resources (ELB, S3 website, CloudFront, etc.), records
TTL Support	✅ Yes (yes specifies TTL)	✅ Yes (TTL auto-managed or configurable)
Chainable?	✅ Yes (can point to another CNAME)	❌ No (must point to a single AWS resource or record)

Sample Scenarios

•  CNAME Record Example:

# text

Name:    web.twtechapp.com

Type:    CNAME

Value:   springapp.twtech.com

•         Use case: Forwarding subdomains to a 3rd-party provider.

 Alias Record Example:

#  text 

Name:    twteceh.com

Type:    A (Alias)

Alias Target:  d123.cloudfront.net (CloudFront distribution)

•         Use case: Pointing a root domain to a CloudFront distribution, which is not possible with a CNAME.

twtech Key Takeaways

•         Use CNAME when pointing subdomains to other domains, non-AWS resources, or where standard DNS behavior is required.
•         Use Alias when pointing to AWS resources, especially at the root domain (zone apex).

Project: Hands-on

How twtech create A records with:  CNAME and Alias

Step-1:

• Go to Route 53 and Select the hosted zone to create A record:  twtech.click

• Create the record of type CNAME: myspringapp.twtech.click

• Assign a name: myspringapp.twtech.click

• Select record type: CNAME

• The value must be a domain name(twtech is using DSN): twtech-Route53-ALB-14518xxx.us-east-2.elb.amazonaws.com

• The idea is, instead of twtech accessing the application via the DNS, it will access it via the record name instead:
• Myspringapp.twtech.net ----------- > twtech-Route53-ALB-145xxx.us-east-2.elb.amazonaws.com
•  Create the record with CNAME:

Step-2:

• twtech verifies that the rocord created with the CNAME is working on: Firefox

NB:

• Accessing A record on the browser is sometime not compactible: it does  work with my:  google chrome in my environment.

• Instead of creating and directing the record to DNS, twtech may also use an Alias:
• Select the hosted zone to be used and double click: twtechnet.uk

• Step-3:
• twtech Creates A record: myalias.twtechnet.uk

• Assign a name: myalias.twtechnet.uk
• Enable Alias and select from the list of Aliases: Alias to Application and Classic Load Balancer.
• Select the region for the application: us-east-2 (Ohio)
• Select the application Load balancer: dualstack.twtech-Route53-ALB-145183xxxx.us-east-2.elb.amazonaws.com
• Enable evaluation of target heath with: Yes
• Create the record with Alias: myalias.twtechnet.uk

Step-4:

• twtech uses the A record with Alias to access the application: myalias.twtechnet.uk
• From firefox, the application is: reachable

• However, it is not accessible from my : google chrome browser

NB:

• The Alias record is free to Query: twtech is not charged

Step-5:

• twtech creates a record and uses the domain apex to direct traffic to the application.
• Select the Hosted zone and click open: twtech.click

• Create  record:

• No Record name
• Record type: A-Routes traffic to an IPv4 address and some AWS resources
• Value : DNS (of ALB)
• Enable Alias and select: Alias to Application and Classic Load Balancer

Step-6:

• twtech verifies that the alias created from domain apex is access on the browser: twtech.click

NB:

• Remember to always try another browser if one does not access the A records.
• Not all browsers are compactible.
• The browser that is compactible for my environment may not be compactible for some other persons.
• This application is already deployed in us-east-2.