Recently for a number of reasons I've been working with individuals that are taking a website and moving them from one hosting provider to another. Sometimes these moves are taking the existing site as is, other times it is migrating to a "new site" at the same time. However, after doing at least 10-12 of these in the past few months a few common points of "confusion" have come to light. As such, due to popular request, I'll lay out the basics of how to move a website from one hosting provider to another and discuss the component parts that are involved in such a move.
What Parts Are Involved
When you look at a website, you have a number of different pieces and parts that are involved. The confusing aspect of these elements is that in certain cases the same company provides multiple services covering different areas. It is in these situations that things become clear a mud, even for the most experienced people that work with websites. Given this confusion, before we talk about moving a site between locations lets ensure that we properly identify all of the components involved.
Domain Name Registrar - This is the company that is responsible for the reservation of your domain. You will typically pay this company anywhere from $2.99/year on up for the "ownership" of the particular domain name that you are using.
DNS Server/Entries - These are the individual naming records that allow computers to translate your domain name into the needed IP Address that identifies the server(s) that are used to serve the content. DNS Entries for individual domains will vary, as the more services involved the more entries you will have. DNS Entries exist in many types, such as A and CNAME records typically used for address identification, MX Records that relate to email, and TXT records which are used for other purposes. These elements are integral to the proper operation of your website.
Hosting Account/Server - This is the actual server, either a portion of a shared server or your own dedicated server. (Regardless of if it is physical or cloud.) This is the place where your content lives. Your server/space will be identified with a unique IP address, a set of numbers similar in format to 192.168.1.1. This is the location where your website files are stored and any related databases etc would be handled.
Site Move Scenarios
Now that we have a high-level knowledge of the individual pieces and parts that are essential for our website. Let's discuss a few of the scenarios that could occur with desired changes and what elements will need to be modified to accomplish the goal.
Moving Website From Company A to Company B
The most simple situation, typically, is moving your website and only the website from Company A to Company B. In this case, your Domain Registrar and DNS is managed by another party, you don't have email to worry about, and you are simply moving the site to a new location. In this case, set up your new hosting account, set up the files on the new server and then when ready, update the A record & any CNAME records that point to the old hosting provider to the new hosting provider.
Typically, this type of change will be effective in around an hour, as the default Time To Live for a particular DNS entry is 1 hour (3600 seconds). However, this is not 100% guaranteed as corporate and other proxies can store DNS entries for a longer period of time.
Moving Website & DNS From Company A to Company B
Often times a hosting company will be providing not only hosting services but also DNS services. This can be identified typically by domains where the Domain Name Registrar has a value of "NS1.CompanyA.com" or similar for the Nameservers. This means that your domain is dependent on the DNS entries that are also stored with your hosting account. In this case, it is important to take a few additional steps to ensure a clean & consistent transition.
You will want to start this process out by manually moving ALL DNS entries from the existing company DNS location to the new company. I often recommend that people do this BEFORE they move the site. This allows you to do things in a phased approach. BY keeping ALL DNS entries the same, you get this information setup at Company B. Now, at your Domain Registrar, you can update the Nameserver values to be pointing to NS1.CompanyB.com. Once you do this, wait 72 hours before proceeding. Nameserver changes are subject to longer propagation delays and are not changes that you can necessarily guarantee will complete in any given time.
If you follow this process, you can then complete the final migration using the steps for the simple Company A -> Company B process outlined above. If email is involved ensure that you migrate this as well.
Moving Domain Registration, DNS, & Hosting from Company A -> Company B
This situation is the most sticky, as the process of moving a domain registration from one company to another is a process that requires an individual to obtain authorization, the current registrar to release the domain and the eventual transfer. Depending on the particular registrar this process can be smooth, or it can be a major pain. As such, there are a few options that you have available depending on which elements are the most important.
Option A: Move the site first. In this case, you will follow the rules for Company A -> Company B move first. Move your site and related servers, but leave the DNS & registration with the current provider. Once you have the site live on the new location, you can double back and move the rest. You will start with moving DNS entries to the new provider so they are ready, and then lastly request the transfer of the domain from Company A to Company B. This works well if you need to move the site quickly, and the rest of the stuff just needs to move to keep things where it should be.
Option B: If your biggest concern is getting out of Company A sooner than later you might take a slightly different approach. Setup the existing DNS entries & site on the new hosting company and immediately request the transfer of the domain to the new hosting company. This can take time, and the important consideration here is that you don't know when the cut-over is going to occur, so if you have a site with lots of activity this can be a bit of a nightmare situation.
This is just two of the options that you could consider for this situation and doesn't discuss email or other services that are most likely involved. If you find yourself in this situation today, read on to the summary for a few recommendations to make your life easier.
Summary
I hope that this high-level situation helps to explain the complexity and component parts that can be involved in the migration of a website from one host, DNS, or registrar to another. The examples included in this post are only a drop in the bucket to the potentials that can occur, but they should get you asking the right questions. If you are encountering a move and don't know where something is, be sure to ask for help FIRST as there is nothing worse than having email or other services go down for a key domain.
One item that I would like to stress is that by following these scenarios it should be fairly visible the importance of following a form of separation of concerns when regards to Domain Registration, DNS and hosting to allow you quick & efficient transitions.