The correct answer is B.
OBJ-2.1: A firewall is an integral part of creating a screened subnet. If configured correctly, it can regulate exactly what traffic and users are allowed to access the server. This is different from a content filter because a content filter denies traffic to a user based on content, but not access to a server. If the firewall ruleset was not configured to allow external users to access the application remotely, the default condition is to “deny by default”. Content filtering is the use of a program to screen and/or exclude access to web pages or emails deemed objectionable. The Dynamic Host Configuration Protocol (DHCP) uses port 67 and is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a client-server architecture. The Domain Name System (DNS) uses port 53 and is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network.