Subdomain Delegation: How to Point a Subdomain to an External Service

A subdomain is a prefix you add to your domain - like app.yourdomain.ca or shop.yourdomain.ca. Subdomains are useful for separating different parts of your online presence while keeping everything under your brand's domain name. When those different parts live on external platforms, you need to configure DNS to point the subdomain to the right service. This is called subdomain delegation.

Common Scenarios Where You Need This

Here are the situations that come up most often:

• app.yourdomain.ca pointing to a web application hosted on Heroku or Railway
• shop.yourdomain.ca pointing to a Shopify store
• status.yourdomain.ca pointing to a Statuspage or Betterstack status page
• help.yourdomain.ca pointing to a Freshdesk or Zendesk help centre
• docs.yourdomain.ca pointing to a GitBook or Notion site

Each of these providers gives you instructions for pointing a custom domain. Those instructions will tell you to either add a CNAME record or delegate the subdomain's nameservers. Understanding the difference helps you follow the instructions correctly.

CNAME Records vs NS Delegation

CNAME (Canonical Name) records are the most common approach. A CNAME points your subdomain to a hostname the external provider controls. For example, Shopify might ask you to create:

shop.yourdomain.ca  CNAME  shops.myshopify.com

When someone visits shop.yourdomain.ca, DNS resolves the CNAME and follows it to Shopify's servers, which then serve your store. The visitor's address bar still shows your domain. CNAME delegation is simple and is what most SaaS platforms use.

NS (Nameserver) delegation is a more complete handoff. Instead of pointing the subdomain to a hostname, you point it to a different set of nameservers that have full control over the subdomain's DNS. For example:

app.yourdomain.ca  NS  ns1.heroku.com
app.yourdomain.ca  NS  ns2.heroku.com

Any DNS queries for app.yourdomain.ca or anything under it are now handled entirely by Heroku's nameservers. This is more powerful - the external provider can create additional records like MX or TXT under that subdomain - but it is also less common. Most platforms ask for a CNAME, not NS delegation.

A key limitation: you cannot use a CNAME record on the root domain (yourdomain.ca itself). CNAMEs only work on subdomains. For root domain pointing, you need A records or ALIAS/ANAME records if your DNS provider supports them.

Step-by-Step in cPanel Zone Editor

To add a CNAME record for a subdomain in cPanel:

1. Log in to cPanel and go to Domains > Zone Editor
2. Click Manage next to your domain
3. Click Add Record
4. Set Type to CNAME
5. In the Name field, enter the subdomain prefix - for example, shop (cPanel will append your domain automatically)
6. In the Record field, enter the hostname your provider gave you - for example, shops.myshopify.com
7. Click Save Record

DNS changes propagate within a few minutes for most providers, though up to 24 hours is possible if your TTL was set high. You can check propagation using a tool like whatsmydns.net.

To add NS records for full subdomain delegation, follow the same steps but select NS as the record type and add one record per nameserver your provider specifies.

One Thing to Check First

Before adding a CNAME record, confirm there is no existing A record for that subdomain. If cPanel already created an A record for shop.yourdomain.ca pointing to your server's IP, you need to delete it before adding the CNAME - you cannot have both simultaneously. In Zone Editor, look for existing records matching your subdomain and remove any A or CNAME conflicts before saving the new one.

Subdomain delegation is a routine DNS task once you have done it once. The instructions from your service provider tell you exactly what to create - your job is just to know where to put it.