Question

which of these ports are used by ftp? (choose two.) 110 25 21 20

Explanation:

FTP (File Transfer Protocol) uses two ports. Port 21 is used for control connections (commands and responses between client and server). Port 20 is used for data connections (actual file transfer). Port 110 is for POP3 (Post Office Protocol 3) and port 25 is for SMTP (Simple Mail Transfer Protocol).

Answer:

21, 20