Redesign changes old-site.com to new-site.com. One .htaccess rule sends everything to the homepage — a thousand articles lose their URLs. Worse: www forces HTTPS which sends to apex which sends to www. The site "won't load": this is not a host outage, it is a redirect loop.
The same scenario appears during registrar change, brand merger or migration to a new host. Each layer — DNS, TLS certificate, CDN, web server — can add its own rule. Without mapping, you stack HTTP hops nobody understands anymore, neither Google nor your support team.
Domain redirects link old and new addresses. Done badly, they cost SEO, skew analytics and erode trust. Done well, they preserve traffic from migration or rebranding. The difference often comes down to one hour of mapping before DNS change.
Redirect types and uses
Each mechanism fits a different case. 301 signals permanent URL or domain change and generally consolidates SEO signals. 302 suits temporary tests or short maintenance — leaving it for months creates ambiguity for search engines. 308 keeps the HTTP method, useful in rare API cases.
CNAME or ALIAS DNS points a name to another host but does not replace HTTP redirect when the visible domain changes. Meta refresh should be avoided: weak signal, poor user experience.
| Code / mechanism | Use | SEO |
|---|---|---|
| 301 | Permanent URL/domain change | Consolidation signal |
| 302 | Temporary (A/B, short maintenance) | No long-term consolidation |
| 308 | Permanent, POST method kept | Rare API cases |
| CNAME / ALIAS | DNS point, not HTTP redirect alone | Add 301 if different domain |
| Meta refresh | Avoid | Weak signal, poor UX |
Avoid classic loops
Start by mapping the full flow: http to https, apex to www or the reverse — one hop, not two conflicting rules. Test with curl -IL https://example.com until you get 200, accepting at most three to five hops.
Enable HSTS only after HTTPS is stable; before fixing loops, HSTS can lock users out for hours. For multi-domain setups, each domain needs one clear canonical target. On CDN, align edge and origin rules to avoid double redirect on the same path.
Common error: SSL on apex, CNAME www to CDN, CDN page redirecting to apex — guaranteed loop.
Domain migration: preserve SEO
First inventory existing URLs via crawl or sitemap. Build an old URL → new URL table with one-to-one 301s — not a global redirect to /. Declare the change in Search Console, publish the new domain sitemap, then monitor 404s and fix top pages.
Update internal links: do not rely on 301s alone forever. If migration coincides with host change, coordinate with choosing a cloud region to avoid two untested simultaneous switches.
The summit: redirect is technical debt visible to Google
Decide and move forward without blind spots
Draw the http, https and www flow before any DNS change, then test with curl and a loop detection tool after each change. On migration, map 301s URL by URL rather than sending everything to the homepage. Compare hosts that clearly document redirect handling via our directory and validate the full journey from a private browser window and from a command-line tool.
Frequently asked questions
301 or 302 for permanent domain change?
Use 301 for a definitive transfer — it generally passes ranking signals. Reserve 302 for temporary tests only; Google may treat a 302 left in place too long differently.
How to detect a redirect loop?
Run curl -IL https://domain.tld, use a redirect checker tool, or inspect the Network tab in browser DevTools. A loop is A → B → A, or a circular http/https/www chain.
Redirect at DNS or server?
HTTP redirect (301) should ideally be written at server or CDN level — cleaner for SEO. DNS redirect or meta refresh is worse; registrar parking is often misconfigured.
Domain migration without SEO loss?
Apply 301s on all useful URLs with an old→new map, declare the change in Search Console, publish the new domain sitemap and monitor 404s — not homepage only.
Before publishing a redirect rule, one command: curl -IL. If the line flickers between two URLs, you did not migrate — you trapped visitors.