PProfessNet Academy
Vercel — deploying frontends/05core10 min

Custom domains and DNS configuration

From *.vercel.app to a custom domain

Every project gets a name.vercel.app address, but in production you want your own domain (e.g. app.professnet.pl). Vercel handles this in a few minutes, automatically issuing an HTTPS certificate.

Adding a domain

  1. Project → Settings → Domains.
  2. Enter the domain, e.g. app.professnet.pl.
  3. Vercel will show which DNS records to add at your registrar/DNS provider.
  4. After DNS propagation, the status changes to Valid and the certificate is issued.

Two ways to route DNS

MethodRecordWhen
Subdomain (e.g. app.)CNAME → cname.vercel-dns.comThe most common case
Root domain (apex professnet.pl)A → 76.76.21.21When you want the bare root
Vercel nameserversNS to VercelFull DNS management in Vercel
# Subdomain - CNAME record at the DNS provider
Type:    CNAME
Name:    app
Value:   cname.vercel-dns.com
TTL:     3600

# Apex domain - A record
Type:    A
Name:    @
Value:   76.76.21.21

Tip: A CNAME record cannot be set on the root (apex) domain per the DNS standard — for professnet.pl use an A record. For subdomains (app., panel.) always prefer CNAME.

Redirecting www → apex (or vice versa)

Add both versions (professnet.pl and www.professnet.pl) and set in Vercel which is primary. Vercel will automatically redirect the second to the first while preserving the path.

HTTPS and certificates

After correct DNS, Vercel issues and renews the Let's Encrypt certificate itself — you do not have to do anything. HTTPS enforcement is the default; HTTP traffic is redirected to HTTPS.

Verification and propagation

DNS propagates from a few minutes to a few hours. You can check it from the terminal:

# Whether the CNAME points to Vercel
dig app.professnet.pl CNAME +short

# Check the A record for the apex
dig professnet.pl A +short

# Whether HTTPS responds
curl -I https://app.professnet.pl

Common pitfalls

  • An old record — remove the previous A/CNAME so it does not collide with the new one.
  • A CDN proxy (e.g. Cloudflare) — with the "orange cloud", set the mode to DNS-only or follow Vercel's instructions, otherwise the certificate will not be issued.
  • A low TTL does not help if the record is simply wrong — first verify the value, then wait for propagation.

Summary

Connecting a domain is: add it in Settings → Domains, set a CNAME (subdomain) or an A record (apex) at the DNS provider, and wait for propagation. Vercel handles HTTPS itself. Verify the records with dig and curl before announcing that the domain works.