Move your web hosting without downtime
Moving a website need not cause any downtime — provided you respect the order of steps. The site is first placed on the new server in full and tested there; only once everything works do you point the DNS at the new environment. Between those two moments, the old site simply keeps running.
Anyone who switches the DNS as the first step is guaranteed to be half online for a while. Below you can read the right order, and where it most often goes wrong in practice.
How a migration runs
Five steps. Only the last one is visible to your visitors, and it is the shortest.
Take stock and gather access
What exactly is running: which CMS, how many sites, how many mailboxes, which databases? Gather the access to your current hosting and to wherever your domain name is managed straight away. Missing credentials are in practice the most common cause of delay — request them in good time.
Lower the TTL on the DNS records
A few days before the move, lower the TTL of your DNS records, for example to 300 seconds. The TTL decides how long the rest of the internet remembers your old details; lowering it in advance turns the later switch into a matter of minutes instead of hours.
Transfer files, database and mailboxes
The complete web space and the database are copied to the new server, and the mailboxes are created there in advance. Your old site stays up meanwhile — nothing changes for visitors yet.
Test before anything is switched
The site is tested on the new server while the DNS is still unchanged. Does the checkout work, do forms arrive, are the images there, does the CMS run on the right PHP version? Whatever turns out to be broken here costs nothing — after the switch it does.
Switch the DNS and check
Only now do you point the DNS at the new environment. Thanks to the lowered TTL that happens quickly. Afterwards it is checked that https works, that no error pages have appeared and that no mail is still arriving on the old server waiting to be collected.
The pitfall: email
Websites rarely migrate badly — email does. The reason is that mail keeps arriving during the switch, and messages can still land on the old server in that window. That is why the mailboxes are created before the DNS change, and why whatever reached the old server is collected after the switch.
If you work with IMAP, your mail lives on the server and its contents can be transferred. With POP3, your mail is already local on your own device and does not move with it — in that case make sure you hold those local mail files safely yourself.
