With either encryption method (WEP or WPA), you can give the password to the customers who need it, and
even change it frequently (daily if you like). So this won't be an inconvenience for the customers.

Integrated Services Digital Network (ISDN) is a digital telephone/telecommunication network that carries voice, data, and video over an existing telephone network infrastructure. It requires an ISDN modem at both the ends of a transmission. ISDN is designed to provide a single interface for hooking up a telephone, fax machine, computer, etc.
ISDN has two levels of service, i.e., Basic Rate Interface (BRI) and Primary Rate Interface (PRI).
Answer option A is incorrect. The Point-to-Point Protocol, or PPP, is a data link protocol commonly used to establish a direct connection between two networking nodes. It can provide connection authentication, transmission encryption privacy, and compression. PPP is commonly used as a data link layer protocol for connection over synchronous and asynchronous circuits, where it has largely superseded the older, non- standard Serial Line Internet Protocol (SLIP) and telephone company mandated standards (such as Link Access Protocol, Balanced (LAPB) in the X.25 protocol suite). PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP), Novell's Internetwork Packet Exchange (IPX), NBF, and AppleTalk.
Answer option D is incorrect. The X.25 protocol, adopted as a standard by the Consultative Committee for International Telegraph and Telephone (CCITT), is a commonly-used network protocol. The X.25 protocol allows computers on different public networks (such as CompuServe, Tymnet, or a TCP/IP network) to communicate through an intermediary computer at the network layer level. X.25's protocols correspond closely to the data-link and physical-layer protocols defined in the Open Systems Interconnection (OSI) communication model.
Answer option B is incorrect. Frame relay is a telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between end-points in a wide area network (WAN). Frame relay puts data in a variable-size unit called a frame. It checks for lesser errors as compared to other traditional forms of packet switching and hence speeds up data transmission.
When an error is detected in a frame, it is simply dropped. The end points are responsible for detecting and retransmitting dropped frames.

THC-Scan and ToneLoc are tools used for war dialing. A war dialer is a tool that is used to scan thousands of telephone numbers to detect vulnerable modems. It provides the attacker unauthorized access to a computer.
Answer option D is incorrect. NetStumbler is a Windows-based tool that is used for the detection of wireless LANs using the IEEE 802.11a, 802.11b, and 802.11g standards. It detects wireless networks and marks their relative position with a GPS. It uses an 802.11 Probe Request that has been sent to the broadcast destination address.
Answer option B is incorrect. Wingate is a proxy server.

EGP stands for Exterior Gateway Protocol. It is used for exchanging routing information between two gateways in a network of autonomous systems. This protocol depends upon periodic polling with proper acknowledgements to confirm that network connections are up and running, and to request for routing updates. Each router requests its neighbor at an interval of 120 to 480 seconds, for sending the routing table updates. The neighbor host then responds by sending its routing table. EGP-2 is the latest version of EGP. Answer option B is incorrect. Internet Control Message Protocol (ICMP) is a maintenance protocol that allows routers and host computers to swap basic control information when data is sent from one computer to another. It is generally considered a part of the IP layer. It allows the computers on a network to share error and status information. An ICMP message, which is encapsulated within an IP datagram, is very useful to troubleshoot the network connectivity and can be routed throughout the Internet. Answer option A is incorrect. Internet Group Management Protocol (IGMP) is a communication protocol that multicasts messages and information among all member devices in an IP multicast group. However, multicast traffic is sent to a single MAC address but is processed by multiple hosts. It can be effectively used for gaming and showing online videos. IGMP is vulnerable to network attacks. Answer option D is incorrect. Open Shortest Path First (OSPF) is a routing protocol that is used in large networks. Internet Engineering Task Force (IETF) designates OSPF as one of the Interior Gateway Protocols. A host uses OSPF to obtain a change in the routing table and to immediately multicast updated information to all the other hosts in the network.