How to configure custom domains and SSL certificates on Vercel?

Configuring custom domains and SSL certificates on Vercel is a straightforward process. Vercel provides automated SSL certificate management, making this process very convenient.

Custom Domain Configuration

1. Adding Custom Domains

Adding via Vercel Dashboard:

Log in to Vercel Dashboard
Select your project
Go to "Settings" → "Domains"
Click "Add Domain"
Enter your domain (e.g., example.com or www.example.com)
Choose domain type:
- Production: For production environment
- Preview: For preview deployments

Adding via Vercel CLI:

bash
# Add production domain
vercel domains add example.com

# Add preview domain
vercel domains add preview.example.com --preview

2. Domain Types

Vercel supports the following domain types:

Root Domain:

example.com
Requires A record or CNAME alias record

Subdomain:

www.example.com
blog.example.com
api.example.com
Uses CNAME record

Wildcard Domain:

*.example.com
Matches all subdomains
Requires paid plan

3. DNS Configuration

Configuration Steps:

Check DNS configuration requirements in Vercel Dashboard
Log in to your domain registrar (e.g., GoDaddy, Namecheap, Cloudflare)
Add appropriate DNS records based on type

A Record Configuration (for root domain):

shell
Type: A
Name: @
Value: 76.76.21.21
TTL: 3600 (or default)

CNAME Record Configuration (for subdomain):

shell
Type: CNAME
Name: www
Value: cname.vercel-dns.com
TTL: 3600 (or default)

Special Configuration with Cloudflare:

If you use Cloudflare as your DNS provider, note:

Proxy Mode:
- When Cloudflare proxy is enabled (orange cloud), Vercel may not correctly verify domain ownership
- Recommend disabling proxy (gray cloud) first, wait for verification, then enable
SSL Mode:
- Set to "Full" or "Full (strict)"
- Do not use "Flexible" mode

4. Domain Verification

Verification Process:

After adding DNS records, Vercel automatically verifies domain configuration
Verification typically takes a few minutes to a few hours (depending on DNS propagation)
Once verified, domain status shows "Valid Configuration"

Verification Checks:

bash
# Check if DNS records are effective
dig example.com

# Check CNAME record
dig www.example.com CNAME

# Check DNS propagation
nslookup example.com

SSL Certificate Configuration

1. Automatic SSL Certificates

Vercel uses Let's Encrypt to automatically provide SSL certificates for your domains:

Features:

Completely free
Automatic renewal
Supports HTTP/2 and HTTP/3
Automatic configuration

Certificate Types:

Single Domain Certificate: Protects a single domain
Wildcard Certificate: Protects main domain and all its subdomains (requires paid plan)

2. Automatic SSL Certificate Management

Automatic Issuance:

After domain verification passes, Vercel automatically issues SSL certificate
Usually completes within minutes
No manual operation required

Automatic Renewal:

Certificates automatically renew 30 days before expiration
No need to worry about certificate expiration
Fully automated

Certificate Monitoring:

Vercel continuously monitors certificate status
Automatically fixes issues when discovered
View certificate details in Dashboard

3. Force HTTPS

Automatic Redirect:

Vercel by default redirects all HTTP requests to HTTPS:

javascript
// Configure in vercel.json
{
  "redirects": [
    {
      "source": "/:path*",
      "has": [
        {
          "type": "host",
          "value": "example.com"
        }
      ],
      "destination": "https://example.com/:path*",
      "permanent": true
    }
  ]
}

HSTS Configuration:

javascript
{
  "headers": [
    {
      "source": "/(.*)",
      "headers": [
        {
          "key": "Strict-Transport-Security",
          "value": "max-age=31536000; includeSubDomains"
        }
      ]
    }
  ]
}

Advanced Configuration

1. Multiple Domain Configuration

Adding Multiple Domains:

Add domains one by one in Domains settings
Configure DNS records for each domain
Wait for all domains to verify

Primary Domain Setting:

javascript
// Set primary domain in vercel.json
{
  "name": "my-project",
  "alias": ["example.com", "www.example.com"]
}

2. Environment-Specific Domains

Preview Environment Domain:

bash
# Add specific domain for preview deployments
vercel domains add preview.example.com --preview

Development Environment Domain:

bash
# Add domain for development environment
vercel domains add dev.example.com --dev

3. Custom 404 Page

Configure Custom 404 Page:

javascript
// Configure in vercel.json
{
  "rewrites": [
    {
      "source": "/404",
      "destination": "/custom-404.html"
    }
  ],
  "notFound": true
}

Troubleshooting

1. Domain Verification Failed

Common Causes:

DNS record configuration error
DNS propagation not complete
Domain already used by another service
Cloudflare proxy mode issue

Solutions:

Check if DNS records are correct
Use DNS checking tools to verify records
Wait for DNS propagation to complete (up to 48 hours)
If using Cloudflare, temporarily disable proxy

bash
# Check DNS records
dig example.com +short

# Check WHOIS information
whois example.com

# Check DNS propagation
dig example.com @8.8.8.8

2. SSL Certificate Issuance Failed

Common Causes:

Domain verification not passed
DNS record configuration error
Firewall blocking Let's Encrypt verification
Domain already used by another certificate

Solutions:

Ensure domain verification passed
Check DNS record configuration
Check firewall settings
Manually trigger certificate re-issuance in Dashboard

3. HTTPS Redirect Not Working

Checklist:

Confirm SSL certificate has been issued
Check redirect settings in Vercel configuration
Clear browser cache
Test in private mode

Best Practices

1. Domain Management

Use version control for domain configuration
Regularly check domain expiration dates
Set up auto-renewal for important domains
Keep backup of domain access credentials

2. SSL Security

Enable HSTS to force HTTPS
Regularly check SSL certificate status
Use strong passwords for domain accounts
Enable two-factor authentication

3. Monitoring and Alerts

Set up domain expiration reminders
Monitor SSL certificate status
Configure website availability monitoring
Set up error alerts

4. Performance Optimization

Use CDN to accelerate static resources
Enable HTTP/2 and HTTP/3
Optimize DNS resolution time
Use modern TLS versions

Frequently Asked Questions

Q1: Can I use free domains?

A: Yes, Vercel supports any legal domain, including free domains. However, it's recommended to use paid domains for better stability and support.

Q2: Is there a limit on SSL certificates?

A: In the free plan, you can add unlimited domains to each project, and each domain automatically receives an SSL certificate.

Q3: How do I migrate an existing domain to Vercel?

Add domain in Vercel
Update DNS records to point to Vercel
Wait for DNS propagation
Verify configuration is correct

Q4: Can I use my own SSL certificate?

A: Vercel does not support uploading custom SSL certificates; you must use the automatically issued Let's Encrypt certificates from Vercel.

Q5: How long does domain configuration take to take effect?

A: Typically takes a few minutes to a few hours, up to 48 hours maximum (DNS propagation time).

Summary

Main advantages of configuring custom domains and SSL certificates on Vercel:

Automated: SSL certificates automatically issued and renewed
Simple: Intuitive configuration interface
Free: Let's Encrypt SSL certificates completely free
Secure: Automatic HTTPS redirect
Reliable: 99.99% uptime guarantee

By following the steps and best practices above, you can easily configure custom domains and SSL certificates on Vercel, providing a secure, professional access experience for your website.