When moving sites to a new server, you can test each one by replacing the DocumentRoot in the 000-default.conf file with the directory containing each site. You might want to do some site tweaking and changing the location for each site can get tedious after a while. The solution is to set up Apache to test virtual servers without domain names. The first step is to edit the /etc/hosts file on the computer that you will be using to visit the sites. Add the sites you wish to test and the IP address at the end of the file.
142.255.228.33 firstsitetotest.com
142.255.228.33 secondsitetotest.com
...
142.255.228.33 lastsitetotest.com
You don’t need to reboot your computer or reload the file to get it to work.
Next, edit the 000-default.conf file in /etc/apache2/sites-available/
I keep my site files in the /www directory.
<VirtualHost firstsitetotest.com:80>
ServerName www. firstsitetotest.com
DocumentRoot /www/firstsitetotest
</VirtualHost>
<VirtualHost secondsitetotest.com:80>
ServerName www.secondsitetotest.com
DocumentRoot /www/secondsitetotest
</VirtualHost>
...
<VirtualHost lastsitetotest.com:80>
ServerName www. lastsitetotest.com
DocumentRoot /www/lastsitetotest
</VirtualHost>
Reload Apache with sudo systemctl reload apache2 and test your config with sudo systemctl status apache2
If the sites currently exist, you should make a small change in the main file to make sure you are being redirected to the new site.