Site Migration
Definition
A site migration is any move that changes where a site lives or what its URLs are. Three kinds are common and they are not equally risky. Changing host while keeping every address is the safest, because nothing outside the site needs to know. Changing domain is riskier, since every link anyone has ever made now points at the old name. Changing URL structure — moving from '/about.html' to '/about/', say — breaks bookmarks and search results even when the host and domain stay put. A redesign that does all three at once is where sites lose half their search traffic, and it is usually impossible afterwards to tell which change did it. Keeping the addresses identical is always the cheapest migration.
Why It Matters
Search rankings attach to URLs, not to content. If an address changes and nothing tells search engines where it went, the page starts again from nothing, and the links pointing at it stop counting. A badly handled move can cost 30 to 50 per cent of organic traffic for months; a carefully handled one is usually a dip of a few weeks. The other half of the cost is invisible: emails, PDFs, QR codes and printed material carrying the old addresses cannot be edited, so redirects are the only thing keeping them alive. Do a migration in a quiet week, never the day before a campaign, and never on a Friday.
How It Works
Work through it in order. Inventory the URLs first: export every address from your sitemap, your analytics and any crawl of the existing site, so you know exactly what exists — a list of 200 pages is a checklist, whereas a vague sense of the site is how pages get lost. Keep the addresses wherever you can, and where you cannot, write a redirect map that pairs each old URL with the single best new one, using a 301 redirect and pointing to a real page rather than the homepage. Well in advance, lower the DNS TTL on the records you will change, from a typical 3600 or 86400 seconds down to 300, and wait out the old value so the short one is actually in effect. Build the new site fully and verify it on a temporary address — every page loading, assets present, forms and downloads working, HTTPS valid — before anything points at it. Move the DNS last, then watch: check the redirects with a crawler, submit the new sitemap, and keep the old host running for a few weeks in case something was missed.
Real-World Example
A design studio moves a 60-page portfolio from an ageing CMS onto static hosting at halvard-portfolio.99helpers.site with its own domain. They export the URL list, find 12 pages nobody had remembered, and rebuild the whole thing with identical paths so no redirect map is needed at all. The TTL goes to 300 seconds four days before the move. The new site is checked page by page on the 99helpers address first, and when the A record finally changes, the switch is complete within ten minutes and search traffic is flat the following month.
Common Mistakes
- ✕Redirecting every old URL to the homepage — search engines treat that as a soft 404 and the ranking of each page is lost rather than transferred
- ✕Changing host, domain and URL structure in one go, so when traffic falls there is no way to tell which change caused it
- ✕Lowering the DNS TTL on the morning of the move, when resolvers are still holding the old 24-hour value and will do so all day
- ✕Switching off the old host immediately, which removes the only way to recover a file or an address you discover was missed
Related Terms
Redirect Map
A list of old URLs paired with the new addresses they should send visitors to. It is the record you keep when you move, rename or retire pages, so links that already exist in the world keep working.
Broken Link
A link that points at a page or file which is no longer there, so the visitor gets an error instead of the thing they clicked for. Most of the time the server answers with a 404.
Domain Transfer
Moving a domain's registration from one registrar to another, while keeping the name itself. It is a deliberate, slow process with an authorisation code, a lock and several waiting periods built in to stop domains being stolen.
DNS TTL
TTL is the number of seconds a DNS answer may be cached before it has to be fetched again. It is set per record, and it decides how long a mistake lasts.
301 Redirect
A 301 redirect is a response telling the browser that a page has moved permanently and giving the new address. The old URL keeps working for anyone who follows the old link, but everything that matters now lives at the new one.
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