You would need to setup whats known as Virtual Hosts in your Apache config. There is a good walk through here for Ubuntu 16.04, The process is fairly similar in every distribution.
In the Create the First Virtual Host File section shows you how to set this up in the file /etc/apache2/sites-available/default.conf as shown below
<VirtualHost *:80>
ServerAdmin webmaster@localhost
DocumentRoot /var/www/html
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
This example accepts all traffic for port 80 and sends it to /var/www/html. This includes all unassigned IP addresses and domains.
To add an assigned domain you would create a file /etc/apache2/sites-available/domain.com.conf and enter the below configuration.
<VirtualHost *:80>
ServerAdmin admin@domain.com
ServerName domain.com
ServerAlias www.example.com
DocumentRoot /var/www/domain.com/public_html
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
Repeating this for each domain/ip and adjusting the values in red.
You will following the remaining steps in the above link to enable these configurations.
by Brennen Bearnes
The Apache web server is the most popular way to serve web content on the internet. Apache has the ability to serve multiple domains from a single server by using a mechanism called "virtual hosts". If a virtual host is configured correctly for each domain, the web server can correctly route traffic to the appropriate files based on the domain name requested. In this guide, we'll demonstrate how to configure Apache virtual hosts on an Ubuntu 16.04 server.
