The DLP documentation section: Configuring Network Prevent for Web Server states that "You can type one or more host or domain names (for example, www.company.com), each on its own line." however, your requirement is to ignore requests going to specific IP addresses.
15.8
16.0
It is possible to enter an IP address, but it will not be resolved to a hostname. This means that if a user accesses a website through a domain name and you have only excluded the IP address related to this domain, the request will not be filtered by the ignore rule.