Explanation/Reference:

The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. PPTP uses a control channel over TCP and a GRE tunnel operating to encapsulate PPP packets. The PPTP specification does not describe encryption or authentication features and relies on the PPP protocol being tunneled to implement security functionality. However, the most common PPTP implementation, shipping with the Microsoft Windows product families, implements various levels of authentication and encryption natively as standard features of the Windows PPTP stack. The intended use of this protocol is to provide similar levels of security and remote access as typical VPN products. Answer option B is incorrect. Encapsulating Security Payload (ESP) is an IPSec protocol that provides confidentiality, in addition to authentication, integrity, and anti-replay. ESP can be used alone or in combination with Authentication Header (AH). It can also be nested with the Layer Two Tunneling Protocol (L2TP). ESP does not sign the entire packet unless it is being tunneled. Usually, only the data payload is protected, not the IP header. Answer option D is incorrect. Secure Socket Tunneling Protocol (SSTP) is a form of VPN tunnel that provides a mechanism to transport PPP or L2TP traffic through an SSL 3.0 channel. SSL provides transport-level security with key-negotiation, encryption, and traffic integrity checking. The use of SSL over TCP port 443 allows SSTP to pass through virtually all firewalls and proxy servers.SSTP servers must be authenticated during the SSL phase. SSTP clients can optionally be authenticated during the SSL phase, and must be authenticated in the PPP phase. The use of PPP allows support for common authentication methods, such as EAP-TLS and MS-CHAP. SSTP is available in Windows Server 2008, Windows Vista SP1, and later operating systems. It is fully integrated with the RRAS architecture in these operating systems, allowing its use with Winlogon or smart card authentication, remote access policies, and the Windows VPN client. Answer option C is incorrect. LWAPP (Lightweight Access Point Protocol) is a protocol used to control multiple Wi-Fi wireless access points at once. This can reduce the amount of time spent on configuring, monitoring, or troubleshooting a large network. This also allows network administrators to closely analyze the network.

Internet Protocol Security (IPSec) is a standard-based protocol that provides the highest level of VPN security. IPSec can encrypt virtually everything above the networking layer. It is used for VPN connections that use the L2TP protocol. It secures both data and password. IPSec cannot be used with Point-to-Point Tunneling Protocol (PPTP). Answer option B is incorrect. The Internet Protocol (IP) is a protocol used for communicating data across a packet-switched inter-network using the Internet Protocol Suite, also referred to as TCP/IP. IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering distinguished protocol datagrams (packets) from the source host to the destination host solely based on their addresses. For this purpose, the Internet Protocol defines addressing methods and structures for datagram encapsulation. The first major version of addressing structure, now referred to as Internet Protocol Version 4 (IPv4), is still the dominant protocol of the Internet, although the successor, Internet Protocol Version 6 (IPv6), is being deployed actively worldwide. Answer option C is incorrect. Point-to-Point Protocol (PPP) is a remote access protocol commonly used to connect to the Internet. It supports compression and encryption and can be used to connect to a variety of networks. It can connect to a network running on the IPX, TCP/IP, or NetBEUI protocol. It supports multi-protocol and dynamic IP assignments. It is the default protocol for the Microsoft Dial-Up adapter. Answer option D is incorrect. Layer 2 Tunneling Protocol (L2TP) is a more secure version of Point-to-Point Tunneling Protocol (PPTP). It provides tunneling, address assignment, and authentication. It allows the transfer of Point-to-Point Protocol (PPP) traffic between different networks. L2TP combines with IPSec to provide tunneling and security for Internet Protocol (IP), Internetwork Packet Exchange (IPX), and other protocol packets across IP networks.

VoIP
Explanation:
The Voice over Internet Protocol (VoIP) is used for routing of voice conversation over the Internet. The VoIP is also known by other names such as IP Telephony, Broadband Telephony, etc. Analog signals are used in telephones in which the sound is received as electrical pulsation, which is amplified and then carried to a small loudspeaker attached to the other phone, and the call receiver can hear the sound. In VoIP, analog signals are changed into digital signals, which are transmitted on the Internet. VoIP is used to make free phone calls using an Internet connection, and this can be done by using any VoIP software available in the market. There are various modes for making phone calls through the Internet. Some of the important modes are as follows: Through Analog Telephone Adapter (ATA) In this mode, the traditional phone is attached to the computer through AT
A. ATA receives analog signals from the phone and then converts these signals to digital signals. The digital signals are then received by the Internet Service Providers (ISP), and the system is ready to make calls over VoIP. Through IP Phone IP Phones look exactly like the traditional phones, but they differ in that they have RJ-45 Ethernet connectors, instead of RJ-11 phone connectors, for connecting to the computers. Computer To Computer This is the easiest way to use VoIP. For this, we need software, microphone, speakers, sound card and an Internet connection through a cable or a DSL modem. Soft Phones Soft phone is a software application that can be loaded onto a computer and used anywhere in the broadband connectivity area.