Migrating Your Web Site In-House

It is important to have a detailed migration plan if you currently use an external company to host your Web site and wish to move the site to a server at home or in your office. At the very least your plan should include these steps:

1. There is no magic bullet that will allow you to tell all the caching DNS servers in the world to flush their caches of your zone file entries. Your best alternative is to request your existing service provider to set the TTL on my-site.com in the DNS zone file to a very low value, say one minute. As the TTL is usually set to a number of days, it will take at least three to five days for all remote DNS servers to recognize the change. Once the propagation is complete, it will take only one minute to see the results of the final DNS configuration switch to your new server. If anything goes wrong, you can then revert to the old configuration, knowing it will rapidly recover within minutes rather than days.
2. Set up your test server in house. Edit the /etc/hosts file to make www.my-site.com refer to its own IP address, not that of the www.my-site.com site that is currently in production. This file is usually given a higher priority than DNS, therefore the test server will begin to think that www.my-site.com is really hosted on itself. You may also want to add an entry for mail.my-site.com if the new Web server is going to also be your new mail server.
3. Test your server based applications from the server itself. This should include mail, Web, and so on.
4. Test the server from a remote client. You can test the server running as www.my-site.com even though DNS hasn't been updated. Just edit your /etc/hosts file on your Web browsing Linux PC to make www.my-site.com map to the IP address of the new server. In the case of Windows, the file would be C:\WINDOWS\system32\drivers\etc\hosts. You may also want to add an entry for mail.my-site.com if the new Web server is going to also be your new mail server. Your client will usually refer to these files first before checking DNS, hence you can use them to predefine some DNS lookups at the local client level only.
5. Once testing is completed, coordinate with your Web hosting provider to update your domain registration's DNS records for www.my-site.com to point to your new Web server. As the TTLs were set to one minute previously, you'll be able to see results of the migration within minutes.
6. Once complete, you can set the TTL back to the original value to help reduce the volume of DNS query traffic hitting your DNS server.
7. Fix your /etc/hosts files by deleting the test entries you had before.
8. You may also want to take over your own DNS. Edit your my-site.com DNS entries with VeriSign, RegisterFree or whoever you bought your domain from to point to your new DNS servers.

Remember, you don't have to host DNS or mail in-house, this could be left in the hands of your service provider. You can then migrate these services in-house as your confidence in hosting becomes greater.

Finally, if you have concerns that your service provider won't cooperate, then you could explain to the provider that you want to test its failover capabilities to a duplicate server that you host in-house. You can then decide whether the change will be permanent once you have failed over back and forth a few times.