Question

Johnny is worried that someone might be able to intercept and decrypt his VoIP phone calls. Which of the following protocols is most closely associated with VoIP?

A. SKYP

B. SLIP

C. S/MIME

D. SIP

Answer 1

D. Session Initiation Protocol (SIP) is an application-layer request-response protocol used for VoIP. SIP is transported by UDP, makes use of TCP, and is vulnerable to sniffing attacks. More details can be found in RFC 2543. Answer A is incorrect because there is no protocol SKYP; the proprietary protocol named Skype offers encryption and is used for a peer-to-peer Internet phone service. Answer B is incorrect because SLIP is used by ISPs for dialup connections. Answer C is incorrect because S/MIME is used to secure email.