There is a certain amount of care needed around domain names when buying an internet business. There are some issues that could arise if the necessary diligence is not undertaken. In order to do so, the relevant domain names that are used in the business need to be searched on a database called Whois for essential information https://who.is/
Here is a summary of the main concerns for a potential buyer:
The search will inform you of ownership- it is easy to be mistaken in thinking the person who registers the domain name is the owner, however unlike trademarks, patents and registered designs, domain names are not owned by the registrant. A registrar is an organisation which manages and administers domain names within the guidelines and rules set by the designated domain name registries.
This will also help you in assessing whether you want the domain name to be transferred to your own choice of registrar).
In searching the domain name, it will also inform you of the renewal date this will alert you if any of the domain names are due for renewal before or after buying the business.
In transferring the business, as a buyer you must ensure that you complete all the formalities required to transfer each and every domain name. It needs to be kept in mind that if a domain name is owned by a proxy, you will not be able to have the domain name transferred unless you have registered entities in the relevant jurisdiction.