CCNA Exam Cram[tm] 2 (Exams 640-821, 640-811, 640-801)

  1. EXEC includes the following:

    • Context-sensitive help for syntax checking, command prompting, and keyword completion. Use the question mark (?) to activate context-sensitive help.

    • Command history that provides a record of recent commands. Use the Up and Down Arrow keys to scroll through the history list. Tab completes a partially entered command.

    • Enhanced editing that enables commands retrieved from the command history to be changed quickly then re-executed. The terminal editing and terminal no editing commands enable and disable enhanced editing.

    • Use the Tab key to allow the router to complete commands after you get a %incomplete command% message.

  2. Examine the status of a router with the following commands: show version , show memory , show protocols , show running-config (or write terminal ), show startup-config (or show configuration ), show interfaces , and show flash .

  3. The Cisco Discovery Protocol (CDP) displays summary information about directly connected devices and operates at the Data Link layer. The show cdp neighbors command displays ID, local and remote port, holdtime, platform, and capability information. The show cdp entry <device id> command displays information about a specific device, including all Layer 3 addresses and Internetwork Operating System (IOS) versions.

  4. The command to back up a router configuration file (copy a configuration file from a router to a Trivial File Transfer Protocol [TFTP] server) is copy running-config tftp . The command to restore a configuration file (copy a configuration file from a TFTP server to a router) is copy tftp running-config .

  5. The commands to set the enable secret, console, and auxiliary passwords on a router are as follows :

    Router(config)#enable password Router(config)#enable secret password Router(config)#line aux Router(config-line)#login Router(config-line)#password password Router(config)#line con Router(config-line)#login Router(config-line)#password password Router(config)#line vty 0 4 Router(config-line)#login Router(config-line)#password password

  6. To create a banner for a router and a description for an interface, use the banner motd (message of the day) and description commands.

  7. Router resource usage, bandwidth consumption, and update synchronization are problems for link state routing protocols. They can be eliminated or reduced by using the following techniques:

    • Lengthening update frequency

    • Exchanging route summaries

    • Using time stamps or sequence numbers

  8. Routing Information Protocol (RIP) can be configured on a router with the following commands:

    Router (config)# router rip Router (config-router)# network <network>

  9. Interior Gateway Routing Protocol (IGRP) can be configured on a router with the following commands:

    Router (config)# router igrp <autonomous system number> Router (config-router)# network <network>

  10. The most important basic commands used to monitor IP with Cisco routers are show ip interface , show ip protocol , and show ip route .

  11. A list of the important access list numeric identifiers follows:

    • 1 through 99 : IP standard access list

    • 100 through 199 : IP extended access list

    • 800 through 899 : IPX standard access list

    • 900 through 999 : IPX extended access list

    • 1000 through 1099 Service Advertisement : Protocols (SAP) access list

  12. Two rules for applying a wildcard mask to an IP address are

    A 1 bit in the wildcard mask indicates that the corresponding bit in the IP address can be ignored. Thus, the IP address bit can be either 1 or 0.

    A 0 in the wildcard mask indicates that the corresponding bit in the IP address must be strictly followed. Thus, the value must be exactly the same as specified in the IP address.

  13. The difference in the capabilities of IP-extended access lists in comparison with IP standard access lists is that standard access lists filter IP traffic based on source IP address or address range. IP extended access lists filter traffic based on source and destination addresses, ports, and many other fields.

  14. Know that the last line of any access list is deny any any (implicit).

  15. A single physical interface can be configured with several virtual subinterfaces. Each subinterface can be configured with different addressing information. Subinterfaces can be created and accessed using the serial interface number followed by a period and a number (such as serial 0.78).

  16. The commands to configure frame relay on a router are:

    • Router (config)# encapsulation frame-relay cisco

    • Router (config)# frame-relay lmi-type cisco

    • Router (config)# interface serial 0

    • Router (config-if)# frame-relay interface-dlci <dlci number>

  17. The basic commands to monitor frame relay activity on a router are show frame-relay pvc , show frame-relay lmi , show frame-relay map , and debug frame-relay lmi .

  18. The commands to configure PPP on a router are:

    • Router (config)# username < name > password <password>

    • Router (config)# interface serial 0

    • Router (config-if)# encapsulation ppp

    • Router (config-if)# ppp authentication chap

  19. The basic commands to monitor PPP activity on a router are show interface and debug ppp chap .

  20. The commands to configure ISDN on a router are:

    • Router (config)# isdn switch-type <switch-type>

    • Router (config)# dialer-list <dialer- group > protocol <protocol-name> permit

    • Router (config-if)# interface bri 0

    • Router (config-if)# encapsulation PPP

    • Router (config-if)# dialer-group <number>

    • Router (config-if)# dialer map <protocol> < next -hop address>

    • name <hostname> speed <number> <dial-string>

    • Router (config-if) dialer idle-timeout <seconds>

  21. The basic commands to monitor ISDN and DDR activity on a router are show controller bri , show interface bri , and show dialer .

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