一些做题的时候感觉容易弄混的东西

ccna_candidate

1.configure default route
Router(config)# ip route 0.0.0.0 0.0.0.0 ip/interface

2.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml
set the gateway of last resort
ip default-network 0.0.0.0
or
ip route 0.0.0.0 0.0.0.0 172.16.2.1

3.
turning on/off cdp globally/on interfaces
Router(config)#cdp run
Router(config-if)#cdp enable

4.
to show icmp packets
Router#debug ip icmp
5.
show process
The first number equals the total utilization and the second one
indicates the utilization due to interrupt routines

6.
Router#show version
uptime, last reboot method

7.
Frame Relay
LMI

8.
A CSU/DSU converts digital signals from a router to a leased line; a modem converts digital signals from a router to a phone line

9.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml

"Serial0 is down, line protocol is down"
This output means you have a problem with the cable, channel service unit/data service unit (CSU/DSU), or the serial line. You need to troubleshoot the problem with a loopback test. To do a loopback test, follow the steps below:
Set the serial line encapsulation to HDLC and keepalive to 10 seconds. To do so, issue the commands encapsulation hdlc and keepalive 10 under the serial interface.
Place the CSU/DSU or modem in local loop mode. If the line protocol comes up when the CSU, DSU or modem is in local loopback mode (indicated by a "line protocol is up (looped)" message), it suggests that the problem is occurring beyond the local CSU/DSU. If the status line does not change states, there is possibly a problem in the router, connecting cable, CSU/DSU or modem. In most cases, the problem is with the CSU/DSU or modem.
Ping your own IP address with the CSU/DSU or modem looped. There should not be any misses. An extended ping of 0x0000 is helpful in resolving line problems since a T1 or E1 derives clock from data and requires a transition every 8 bits. B8ZS ensures that. A heavy zero data pattern helps to determine if the transitions are appropriately forced on the trunk. A heavy ones pattern is used to appropriately simulate a high zero load in case there is a pair of data inverters in the path. The alternating pattern (0x5555) represents a "typical" data pattern. If your pings fail or if you get cyclic redundancy check (CRC) errors, a bit error rate tester (BERT) with an appropriate analyzer from the telco is needed.
When you are finished testing, make sure you return the encapsulation to Frame Relay.

CIR = committed information rate (= mean time)

10.
characteristics of Frame Relay point-to-point subinterfaces
a. a unique subnet within a routing domain
b. emulate leased lines

11.
RIPv2 manual route summarization

12.
two things will a router do when running a distance vector routing protocol
a. Send periodic updates regardless of topology changes.
b. Up date the routing table based on updates from their neighbors.

13.
Routing table   longest matching

14.
show ip arp
age "-" means static or local interfaces

15.
ping ICMP layer 3, not related to layer 7

16.
ACL differentiate between source and destination addresses

17.
SSH TCP22
Telnet TCP23
SMTP TCP25

18.
switch remote vty
a. The switch must be configured with an IP address, subnet mask, and default gateway
b. The switch must be reachable through a port connected to its management VLAN.

19.
private ip
10.0.0.0/8-10.255.255.255/8
172.16.0.0/16--172.31.255.255/16
192.168.0.0/24-192.168.255.255/24

Class        Address Range        Supports
Class A        1.0.0.1 to 126.255.255.254        Supports 16 million hosts on each of 127 networks.
Class B        128.1.0.1 to 191.255.255.254        Supports 65,000 hosts on each of 16,000 networks.
Class C        192.0.1.1 to 223.255.254.254        Supports 254 hosts on each of 2 million networks.
Class D        224.0.0.0 to 239.255.255.255        Reserved for multicast groups.
Class E        240.0.0.0 to 254.255.255.254        Reserved for future use, or Research and Development Purposes.

20.
OSPF
a. provides common view of entire topology
b. alculates shortest path
c. utilizes event-triggered updates

21.
Question 73
routing ptotocols only advertises on seletcted networks

22.
Question 77
valid modes for a switch port used as a VLAN trunk
on (legacy), dynamic desirable, auto
nonegotiate

23.
OSPF
area 0 being backbone
OSPF topological database based on hello packets and LSAs

24.
(config)# ip default-gateway
Specify default gateway (if not routing IP)   works only when ip routing is disabled "no ip routing"

25.?
default-information originate [always] [metric metric-value] [metric-type type-value] [route-map map-name]
to advertise default route in routing protocol?
always?

26.
IPv6 address
:: can't be at the end with the exception of [::]

27.
Differentiate switches and hubs

28.
Administratively down ==> both physical and data link down

29.
Router#show cdp neighbors *
Interface: Serial0/1/0, Port ID (outgoing port): Serial0/3/0
Local interface, remote interface

30.
Different router interfaces must be in different subnets

31.
ACL
Router(config-line)# access class
Router(config-if)#ip access-group

32.
OSPF Router ID
highest logic interface IP address, then highest physical interface IP address

33.
CDP layer 2
Layer 2 sublayers: media access control (MAC) and logical link control (LLC)

34.
prevent loops in a layer 2 network: 802.1d and STP

35.
IGRP classful

36.
VLAN database vlan.dat saved on flash

37.
A CSU/DSU terminates a digital local loop.
A modem terminates an analog local loop.

38.
RIP metric 16 ==>Route poison, remove route from routing table

39.
Ethernet multicast: CDP, VTP, STP

/yl/yl

sagacity

xdFnfgnsfgmsfmty

瞬。

c4919654

px5285177

顶起来