A client packet is received by a server. The packet has a destination port number of 143. What service application is the client requesting?

The client packet with a destination port number of 143 is requesting the IMAP (Internet Message Access Protocol) service. Port 143 is the standard port used by IMAP, which is a protocol for accessing email on a remote server from a local client. IMAP allows clients to read emails as if they were stored locally on their device, but actually, the emails are maintained on the server.

As for the other options:

• SMB/CIFS: The Server Message Block (SMB) protocol and the Common Internet File System (CIFS) are used for file sharing, printer sharing, and other network communication tasks. These protocols typically use port 445 or 139, not port 143.
• HTTPS: HTTPS (Hypertext Transfer Protocol Secure) is used for secure communication over a computer network within a web browser and typically uses port 443. It is not related to port 143.
• SLP (Service Location Protocol): SLP is used for computers and other devices to find services in a local area network without prior configuration. It typically uses port 427, not port 143.

Therefore, a packet with a destination port number of 143 is specifically requesting IMAP services.