0 — Test 596

Correct Answer: C. Control on 21; data on 20
Explanation: Passive mode uses a dynamically chosen high port for data.

Correct Answer: B. Telnet sends everything, including passwords, in plaintext; SSH encrypts the session
Explanation: Telnet is considered insecure and should not be used on untrusted networks.

Correct Answer: A. SMTP
Explanation: POP3 and IMAP retrieve mail for clients. MIME is an encoding standard, not a transfer protocol.

Correct Answer: C. IMAP keeps mail on the server and synchronizes it across devices; POP3 typically downloads mail and removes it from the server
Explanation: IMAP uses ports 143 and 993 (TLS). POP3 uses ports 110 and 995 (TLS).

Correct Answer: D. Discover, Offer, Request, Acknowledge
Explanation: DHCP uses UDP port 67 on the server side and 68 on the client side. ALSO KNOW (related points): • How does IMAP differ from POP3? → IMAP keeps mail on the server and synchronizes it across devices; POP3 typically downloads mail and removes it from the server • Which service does UDP NOT provide? → Guaranteed, in-order delivery

Correct Answer: C. UDP 161
Explanation: SNMP traps are sent to UDP port 162.

Correct Answer: A. Each request is independent; the server keeps no client state between requests unless cookies or sessions are used
Explanation: Cookies, tokens, and server-side sessions are added on top of HTTP to maintain state.

Correct Answer: A. QUIC, which runs over UDP
Explanation: A common misconception is that every version of HTTP runs over TCP. ALSO KNOW (related points): • Why is SSH (port 22) preferred over Telnet (port 23)? → Telnet sends everything, including passwords, in plaintext; SSH encrypts the session • How is a file attachment sent in an email? → It is encoded using MIME (for example, Base64) within the message

Correct Answer: C. It is a network-layer protocol with no port numbers
Explanation: ICMP messages are carried directly inside IP packets.

Correct Answer: B. It sends packets with increasing TTL values and records the ICMP 'Time Exceeded' replies
Explanation: Each router decrements the TTL and reports back when it reaches 0.