Test a website before DNS migration: method + checklist (2026)

Migrating a website to a new server is always stressful. What if something doesn't work? What if the site is inaccessible for hours? The solution: test your new server BEFORE changing DNS, using the hosts file.

Why test before migration?

Risks of direct migration

• Downtime: If the new server has a problem, your site is down
• SSL Certificate: Let's Encrypt can fail if misconfigured
• Server configuration: PHP version, missing modules, .htaccess...
• Database: Connections, performance, corrupted data
• Paths and links: Hardcoded URLs, absolute paths

The hosts file advantage

By modifying your hosts file, you point the domain to the new server only on your machine. The rest of the world continues accessing the old server.

Result: you can test for hours without impacting your users.

Step 1: Get the new server's IP

Connect to your new server/host and note the IP address.

At common hosts

SiteGround / Bluehost

• cPanel > Server Information > IP Address

Cloudways / DigitalOcean

• Dashboard > Server > IP Address

AWS / GCP

• Instance > Public IP

Netlify / Vercel

• Deploy settings > Domain settings

Step 2: Modify the hosts file

On Mac

sudo nano /etc/hosts

Add at the end:

# Temporary migration - DELETE after migration
203.0.113.50    www.mysite.com
203.0.113.50    mysite.com

Replace 203.0.113.50 with your new server's IP.

On Windows

1. Open Notepad as administrator 2. File > Open > C:\Windows\System32\drivers\etc\hosts 3. Add the same lines

Flush DNS cache

Essential after modification:

# Mac
sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

# Windows
ipconfig /flushdns

Step 3: Tests to perform

Basic test

1. Open your browser in private/incognito mode 2. Go to https://www.mysite.com 3. The site should display from the new server

Verify you're on the right server

Create a temporary test file on the new server:

echo "NEW SERVER" > /var/www/html/test-migration.txt

Then access https://www.mysite.com/test-migration.txt

Don't forget to delete this file afterwards!

Complete test checklist

Pages and navigation

• [ ] Homepage
• [ ] Internal pages (at least 5)
• [ ] Contact forms
• [ ] Login/signup pages

Features

• [ ] Internal search
• [ ] Cart / e-commerce
• [ ] Member area
• [ ] API / endpoints

Media

• [ ] Images display
• [ ] Videos play
• [ ] PDFs downloadable
• [ ] Uploads work

Performance

• [ ] Acceptable load time
• [ ] No 500/503 errors
• [ ] Cache works

Step 4: Verify SSL certificate

This is crucial. A misconfigured certificate = site inaccessible via HTTPS.

Visual verification

• Green padlock in address bar
• No security warning

Certificate verification

Click the padlock > Certificate > Verify:

• Correct domain
• Validity date
• Issuer (Let's Encrypt, Sectigo, etc.)

Common SSL problems

"NET::ERR_CERT_COMMON_NAME_INVALID" The certificate isn't issued for this domain. Regenerate it.

"Certificate expired" The certificate wasn't renewed on the new server.

Step 5: Proceed with DNS migration

Once all tests pass:

1. Connect to your registrar (GoDaddy, Namecheap, Cloudflare...) 2. Modify the A records to point to the new IP 3. Wait for propagation (minutes to 48h depending on TTL)

Check propagation

Use whatsmydns.net to see global status.

Step 6: Post-migration cleanup

Remove hosts entries

Once propagation is complete:

sudo nano /etc/hosts

Delete the lines added for migration.

Flush DNS cache one last time

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

Verify everything works

Test from another device (phone on cellular) to confirm the new server is responding.

Special cases

Migration with CMS change

If migrating WordPress to another CMS, also test:

• 301 redirects from old URLs
• Updated XML sitemap
• Internal links functional

E-commerce migration

Additional critical points:

• Payment gateways
• Webhooks (Stripe, PayPal)
• Transactional emails
• Stock and pending orders

Sites with CDN (Cloudflare)

If using Cloudflare: 1. Cloudflare proxy uses its own IPs 2. Test in "DNS only" mode (grey cloud) 3. Re-enable proxy after validation

Automate with Locahl

To easily manage these temporary hosts modifications:

• Create a "Migrations" group
• Enable/disable with one click
• Modification history
• No risk of syntax errors

Complete migration checklist

Before migration

• [ ] Full backup of current site
• [ ] Note new server IP
• [ ] SSL configured on new server
• [ ] Current DNS with reduced TTL (300s)

During tests

• [ ] Hosts file modified
• [ ] DNS cache flushed
• [ ] All tests passed
• [ ] SSL certificate validated

After DNS migration

• [ ] Propagation verified
• [ ] Site accessible everywhere
• [ ] Hosts entries removed
• [ ] Old server kept 7 days (backup)

Conclusion

Testing before migrating is the key to stress-free migration. The hosts file gives you a perfect test environment, invisible to your users. Take time to verify everything before changing official DNS.