CISSP Practice полностью

274. What is the most frequent source of local-area network (LAN) hardware failures?

a. Repeater

b. Server disk drives

c. Network cabling

d. Server software

274. c. Hardware failures are grouped as follows: network cabling (60 to 80 percent), repeater (10 to 20 percent), and server disk drive (10 to 20 percent). Cables should be tested before their first use, rather than after a problem surfaces. Testing an installed cable is a tedious job, particularly when there are many network connections (drops) and the organization is large. Failures result when electrical conductors either break open, short together, or are exposed to electromagnetic forces. Failures are also caused when cables are poorly routed. Cabling, unlike other computer equipment, is not protected from heat, electrical charges, physical abuse, or damage.

Repeaters, server disk drives, and server software are incorrect. A repeater repeats data packets or electrical signals between cable segments. It receives a message and then retransmits it, regenerating the signal at its original strength. Server disk drives and server software are comparatively safe and trouble-free devices compared with cabling.

275. Which of the following internetworking devices sends traffic addressed to a remote location from a local-area network (LAN) over the wide-area network (WAN) to the remote destination?

a. Bridge

b. Router

c. Brouter

d. Backbone

275. b. A router sends traffic addressed to a remote location from the local network over the wide area connection to the remote destination. The router connects to either an analog line or a digital line. Routers connect to analog lines via modems or to digital lines via a channel-service unit or data-service units.

Bridge is incorrect because it is a device that connects similar or dissimilar LANs to form an extended LAN. Brouters are incorrect because they are routers that can also bridge; they route one or more protocols and bridge all other network traffic. Backbone is incorrect because it is the high-traffic-density connectivity portion of any communications network.

276. Which of the following protocols use many network ports?

a. SNMP and SMTP

b. TCP and UDP

c. ICMP and IGMP

d. ARP and RARP

276. b. TCP and UDP protocols are part of the TCP/IP suite operating at the transport layer of the ISO/OSI model. Network ports are used by TCP and UDP, each having 65,535 ports. Attackers can reconfigure these ports and listen in for valuable information about network systems and services prior to attack. SNMP and SMTP are application layer protocols, which use few ports. ICMP and IGMP are network layer protocols, which do not use any ports. ARP and RARP are data link layer protocols, which do not use any ports.

Network ports 0 through 1,023 are assigned for service contact used by server processes. The contact ports are sometimes called “well-known” ports. These service contact ports are used by system (or root) processes or by programs executed by privileged users. Ports from 1,024 through 65,535 are called registered ports. All incoming packets that communicate via ports higher than 1,023 are replies to connections initiated by internal requests. For example, Telnet service operates at port #23 with TCP and X Windows operate at port #6,000 with TCP.

277. Which of the following is not compatible with the Internet Protocol (IP) version 6?

a. IP version 4

b. TCP

c. UDP

d. BGP

277. a. The Internet Protocol version 6 (IPv6) is not backward compatible with IPv4 but is compatible with TCP, UDP, ICMP, IGMP, OSPF, BGP, and DNS. The IPsec services are provided at the IP layer (network layer), offering protection for IP and/or upper-layer protocols such as TCP, UDP, ICMP, IGMP, OSPF, BGP, and DNS.

278. Which of the following network connectivity devices use rules that could have a substantial negative impact on the device’s performance?

a. Sensors and switches

b. Routers and firewalls

c. Guards and gateways

d. Connectors and concentrators