Show Answer


The correct answer is A.

OBJ-1.5: The Hypertext Transfer Protocol (HTTP) uses port 80 and is an application layer protocol for distributed, collaborative, hypermedia information systems using unencrypted data transfer. 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. If the outbound port 80 is not open, then users will not be able to connect to a remote web server. If the outbound port 53 is not open, then the users will be unable to conduct a DNS name resolution and determine the IP address of the given web server based on its domain name. Port 22 is used for SSH/SCP/SFTP. Port 143 is used for IMAP. Port 139 and 445 are used for SMB. Port 389 is used for LDAP. Port 110 is used for POP3.

Hide Answer