DNS Cheatsheet

Cname

To create a CNAME record, you need specific pieces of information related to your domain and the target you’re pointing to. Here’s how to gather all the necessary information step-by-step:

1. Understand What a CNAME Record Is

A CNAME record (Canonical Name Record) maps one domain name (alias) to another domain name (canonical name). For example, you might use a CNAME to make www.example.com point to example.com or to point a subdomain to an external service like mail.example.com to mail.provider.com.

2. Required Information for a CNAME Record

Alias Name: The domain or subdomain you’re creating the CNAME record for. Examples: www (for www.example.com). blog (for blog.example.com). This is the name field in your DNS settings.

Canonical Name (Target): The domain or hostname you want the alias to point to. Examples: example.com (if you’re pointing www.example.com to example.com). custom.serviceprovider.com (if you’re using an external service like email or CDN).

TTL (Time-to-Live): This determines how long the DNS resolver should cache the record before checking for updates. Most DNS providers use a default TTL (e.g., 300 seconds or 1 hour). You can usually leave this as the default unless advised otherwise.

3. Where to Find This Information

Alias Name: Decide which subdomain you want to point. Examples: Use www for a www.example.com record. Use mail for mail.example.com.

Canonical Name: Provided by the service or host you’re pointing to. Examples: If you’re pointing to the root domain, the canonical name might be example.com. If pointing to a service, the provider typically gives you a specific hostname (e.g., cname.serviceprovider.com).

TTL: Check your DNS provider’s settings for default values, or set one manually if required.

4. Steps to Gather Information

Log in to Your Hosting/DNS Manager: Access your DNS settings through your hosting provider (e.g., cPanel, Cloudflare, Namecheap).

Check Your Service Provider: If pointing to an external service (e.g., email, CDN, or custom hosting), refer to their documentation or support portal for the correct target (canonical name). Examples: Email hosting: If you’re setting up email through a provider like G Suite or Office365, they will provide the exact CNAME target. CDN/Custom Service: Providers like Cloudflare or AWS Route53 will give you a specific CNAME value to use.

Verify Existing DNS Records: If you’re adding a CNAME to an existing setup, check your current DNS records to avoid conflicts.

5. Example: Setting Up a CNAME for www

If you want to point www.example.com to example.com:

Alias Name: www Canonical Name: example.com TTL: Use default (e.g., 3600 seconds).

6. Tips for CNAME Configuration

Do Not Use CNAME for Root Domains: Most DNS systems do not allow CNAME records on root domains (e.g., example.com). Use an A record instead. Check for Existing Conflicts: Ensure the alias (subdomain) does not already have an A or CNAME record. Verify Changes: Use tools like nslookup, dig, or online DNS checkers to confirm the CNAME record is active after propagation.

If you’re working with a specific provider or service, I can guide you through the exact process for their setup!