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Flashcards in Network Fundamentals Deck (147)
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1
Q

Tell me about global unicast

A

usually /3 3 bits beginning 45 bits global routing prefix 16 bits subnet id 64 bits interface id

2
Q

Tell me about ipv6 multicast

A

FF as first two hexadecimal digits
FF02:1 all nodes in local scope
FF02:2 all routers in scope
8 bits of 1, Flags for 4 bits, Scope for 4 bits, Group ID for 112 bits
ORPT for flags, if R is set to 1 P and T set to 1 (rendezvous point)

3
Q

Tell me about link local address

A

FE80::interface ID
10 Bits Mask + 54 bits 0’s + Interface ID
Can only communicate on network segment

4
Q

Unique Local Address

A

FC00::/7 cannot be routed over public internet (think of it as a private address) eighth bit in first octet is local bit if L is 1 it’s locally assigned

5
Q

Loopback Address

A

::1 aka localhost can be used to verify Ipv6 stack is operating on a device

6
Q

Unspecified Address

A

128 bits are all 0’s :: Used for source address with sending neighbor or router a solicitation (Network advertisement for ip address of the interface) message

7
Q

Solicited Node Multicast

A

corresponding to Ipv6 address in each interface of router begins with FF02::1:FF for first 104 bit, last 24 bits of Ipv6 address, used for duplicate address detection

8
Q

How do we get the EUI address

A

Take Mac address and use it to scale to 64 bit:
Split down middle, insert FFFE in the middle
Convert second hex to binary and flip the 7th bit

9
Q

IPv6 Addresses have

A

Interface ID
Subnet
Global Routing Prefix

10
Q

What does dual stack mean

A

when you run IPv4 and IPv6 on a network

11
Q

Interface ID always occupies the ___ of a Ipv6 address

A

Last 1/2 or 64 bits

12
Q

Class A address has range of

A

1-126 Default mask /8

13
Q

Class B address has range of

A

128-191 Default mask /16

14
Q

Class C address has range of

A

192-223 Default mask /24

15
Q

Class D address is used for ___ and has a range of __

A

multicast, 224-239

16
Q

Class E address is used for ___ and has a range of ___

A

experimental purposes, 240-255

17
Q

Private address ranges

A

A: 10.0.0.0 - 10.255.255.255
B: 172.16.0.0 - 172.31.255.255
B: 169.254.0.0 - 269.254.255.255
C: 192.168.0.0 - 192.168.255.255

18
Q

What’s CDP

A

Cisco Discovery protocol, layer 2 shows information of CDP adjacent devices

19
Q

What destination mac address does CDP send to

A

multicast 01-00-00-0C-CC-CC-CC

20
Q

How do you show neighbors in CDP

A

show cdp neighbors

21
Q

What’s LLDP also known as

A

IEEE 802.1AB

22
Q

What’s the command to know LLDP’s neighbors

A

show lldp neighbors

23
Q

How do you enable LLDP

A

lldp run

24
Q

What are the steps to booting up a router?

A
  1. POST (Power on self test)
  2. Execute bootstrap code to locate and load iOS
  3. Locate Cisco iOS software
  4. Load Cisco iOS Software
  5. Locate Configuration in NV ram
  6. Load into running-config
  7. Execute Configuration
25
Q

Configuration Register

A

16 bit value = 4 hex, last value is boot field (4 bits)

26
Q

What are the different configuration options

A

0x0 = boot into ROM Monitor Mode
0x1 Boot first image in flash
0x2 - 0xF Get image loading instructions from configuration in NVRAM

27
Q

How do you show a router’s license?

A

show license

28
Q

How do you install a router’s license

A

license install (location of xml file)

29
Q

What does ping send?

A

Sends ICMP echo request and listens for an ICMP echo reply back ICMP = internet control message protocol or basically troubleshooting message

30
Q

How do you trace a router

A

trace ip (dest ip) will send a UDP message with incorrect dest port number packet times out at each router and ip is returned

31
Q

What do you use terminal monitor for

A

When you cannot see debug message via telnet or ssh

32
Q

What does DHCP stand for

A

Dynamic Host Config Protocol - can go request iP information from DHCP server

33
Q

What are the steps in a DHCP exchange

A

DORA Discover broadcast (looking for DHCP server), Offer (DHCP server sends an offer back to client with IP Address), Request (info from specific server), Acknowledgement (sends IP address)

34
Q

What is Administrative distance

A

the reliability of a routing protocol; helps a router select the best path when multiple are available - the lower the better

35
Q

What is the administrative distance of a direct connection

A

0

36
Q

What is the administrative distance of a static connection

A

1

37
Q

What is the administrative distance of a eBGP protocol

A

20

38
Q

What is the administrative distance of a EIGRP protocol

A

90

39
Q

What is the administrative distance of a OSPF protocol

A

110

40
Q

What is the administrative distance of a RIP protocol

A

120

41
Q

What are the three packet forwarding options and how do they work?

A

Process switching, cpu looks through each and every decision
Fast switching has a route cache which memorizes what comes through so not everything has to pass CPU
Cisco Express Forwarding has a FIB with a routing table and adjacency table which allow data to go directly without touching CPU

42
Q

How do you check an ip routing table? (command)

A

show ip route

43
Q

What is the format for interface addressing

A

Module/slot/port
Module: what controls it (starts at 0 which is motherboard)
Port: numbering starts at 0, moves from right to left and bottom to top

44
Q

How do you check Cisco iOS (command)

A

show version

45
Q

How do you view Cisco router configuration (command)

A

show running-config

46
Q

How do you view interface status (command)

A

show ip interface brief

47
Q

how do you get to a certain interface (command)

A

show interface (interface id 0/0)

48
Q

How do you reconfigure a router’s hostname (command)

A

config# hostname (hostname)

49
Q

How do you assign an IPv4 to interface

A
# inferface fa0/0
(config-if) ip address (ip address) (mask)
50
Q

How do you assign an iPv6 to interface

A
(config-if) ipv6 enable
ipv6 address (address)/mask
51
Q

How do you assign an iPv6 to interface

A
(config-if) ipv6 enable
ipv6 address (address)/mask
52
Q

What’s the structure of an ethernet frame

A

7 bytes preamble 1 byte SFD which tells next bit is mac address 6 byte destination mac address 6 bytes source mac address 2 byte type Frame check sequence 4 bytes

53
Q

What is a shared segment?

A

It’s a segment where only one frame can travel on the shared segment at any time

54
Q

What is the split horizon rule

A

A rule used by routing protocols where a router advertising a route out of the interface on which the route was learned is prevented to prevent overriding

55
Q

What’s the two numbers on a routing table ie 90/120

A

Administrative Distance/Metric (how far a remote network is from a router dependent on routing protocol used)

56
Q

How do you pull up a routing table for OSPF

A

show ip ospf rib

57
Q

How do you pull up Cisco express forwarding routing table

A

show ip cef

58
Q

How does a router on fast ethernet know about the destination Mac address

A

It sends out an Address Resolution Protocol or ARP broadcast

59
Q

How do you show ARP mac addresses

A

show ip arp

60
Q

how do you calculate the wild mask address

A

Subtract a network’s subnet mask from 255.255.255.255

61
Q

What’s the purpose of a passive interface

A

prevents Hello messages from being sent out of a certain interface while still allowing network to be advertised

62
Q

What does passive interface default do?

A

Suppresses any hello messages from being sent out of any router interface participating in routing protocol

63
Q

What does the network command do?

A

Tells the router which interfaces should participate in the routing process do network ip address wildcard address

64
Q

What prevents RIP from being expanded to larger networks

A

RIP has a max hop count of 15, that is any network with hop count 16 is deemed unreachable

65
Q

What prevents RIP from being expanded to larger networks

A

RIP has a max hop count of 15, that is any network with hop count 16 is deemed unreachable

66
Q

What is convergence

A

RIP - amount of time a dynamic routing protocol takes to reroute around a network failure

67
Q

What is summarization

A

routing protocol feature that allows multiple routes to be represented by a summary route (takes common bits and makes them a mask)

68
Q

What’s the difference between a interior gateway protocol and exterior gateway protocol

A

Interior gateway protocol is a routing protocol running within an autonomous system
Exterior gateway protocol is a routing protocol running between autonomous systems

69
Q

What are some examples of interior and exterior gateway protocol

A

Interior: RIP, OSPF, EIGRP
Exterior: BGP (Border Gateway Protocol)

70
Q

What are the three classifications of routing protocols

A

Distance-Vector: Given a path and metric for each network to connected peers, EIGRP and RIP
Link-State: Each router advertises state of links to every other router creating a topography, then uses Dijkstra, OSPF and ISIS
Path Vector - knows the exact path taken by adding each network in path and forwarding advertisements, BGP

71
Q

What protocol does RIP use

A

Distance Vector

72
Q

What protocol is OSPF

A

Link State

73
Q

What protocol is EIGRP

A

Advanced Distance Vector (if network changes then update)

74
Q

What protocol is BGP

A

Path Vector

75
Q

What’s the difference between RIPv1 RIPv2 and RIPng

A

RIPv1: Broadcasts to advertise to neighbors, No VLSM
RIPv2: Multicast to 224.0.0.0/9, VLSM, IPv4
RIPng: Multicast to FF02::9 VLSM support and IPv6

76
Q

What’s a poison reverse

A

lost a connected network, so router will send a router advertisement of connection with 16 hop count to prevent traffic being sent down

77
Q

How do you view protocol?

A

show ip protocols

78
Q

What’s a collision

A

Two stations transmitting a shared segment at the same time

79
Q

What’s jamming

A

continued transmission of a frame that has collided to allow all devices on a segment to detect the collision

80
Q

What’s an ethernet hub

A

all ports on an ethernet hub belong to the same collision domain

81
Q

What’s the ethernet switch

A

Each port is in its own collision domain

82
Q

What’s the difference between duplex and half-duplex

A

Duplex can send and receive at the same time, Half Duplex cannot send/receive at the same time

83
Q

What’s a broadcast domain

A

Defines how a broadcast travels in a network, which contains the destination mac address

84
Q

All ethernet hub ports

A

belong to the same broadcast domain and collision domain

85
Q

All ports on ethernet switch will

A

belong to the same broadcast domain but separate collision domains

86
Q

All ports on a router belong to

A

a separate broadcast domain and different collision domain

87
Q

If a switch does not know a Mac address, what does it do?

A

It floods the ports, that is it sends frames out of all ports except the received port;

88
Q

What’s an ARP broadcast

A

Flooded through FFFF.FFFF.FFFF

89
Q

What’s the naming format for an interface in a switch

A

switch in stack/slot in module (0)/port number

90
Q

How do you show a mac address table

A

show mac address-table

91
Q

How do you see a current configuration on a switch

A

show run

92
Q

How do you set an enable password on a Cisco switch

A

in config mode type enable password cisco or enable secret (password)

93
Q

How do you set exec timeout on a Cisco switch

A

In line config mode type: exec-timeout (min) (sec)

94
Q

Explain the working behind a mac flooding attack

A

A hacker can connect to a switch and overflow the CAM or Mac address table; at the same time the switch since it doesn’t know the dest. mac address so it floods frames out of all ports

95
Q

What’s the pre-requisite for port security

A

the port has to be an access port (cannot be trunked)

96
Q

How do you turn on security?

A

get into the interface
switchport mode access
switchport port-security

97
Q

How do you specify the max # of mac addresses?

A

switchport port-security maximum (number)

98
Q

How do you specify a mac address

A

switchport port-secuirty mac-address (number)

99
Q

To set up sticky or dynamic learning

A

switchport port-security mac-address sticky

100
Q

What are the port security violation options

A

protect - mac addresses not allowed are dropped
restrict - drop disallowed and increment security violation counter
shutdown - switch will shut down

101
Q

How do you remove a port out of err disable

A

go to port and put no shutdown

102
Q

To see port security type, type

A

show port-security

103
Q

How do you change recovery time on error disable port automatic recovery

A

errdisable recover cause psecure-violation

104
Q

To change error disable port automatic recovery type

A

errdisable recover interval (time in sec)

105
Q

Shut down all unused ports and put them in an unused VLAN

A
conf term
vlan 999
name NULL_VLAN
int range fa 1/0/1 - 24
shutdown 
end

to turn on, go to port and say no shutdown

swithcport access vlan 9999
show vlan

106
Q

How do you show an access list?

A

show access-lists

107
Q

What does trunking add to a frame?

A

It tags them, adding 4 bytes - 12 bits to the id of the VLAN and 3 bits to the priority/quality of service

108
Q

Explain the 4 trunking modes and what they entail

A

access - forces a port to become an access port
trunk - forces a port to become a trunk port and will send DTP frames
dynamic desirable - initiates negotiation of a trunk
dynamic auto - passively waits for the remote switch to initiate negotiation of a trunk (if it only receives one)

109
Q

What does DTP stand for

A

Dynamic Trunking Protocol

110
Q

How do you view trunking

A

show interfaces fa 1/0/12 switchport

111
Q

How do you show trunks on a switch?

A

show interfaces trunk

112
Q

How do you pick which VLANs are allowed to flow over a trunk?

A

switchport trunk allowed vlan ?`

113
Q

How do you check interface status for a particular interface

A

show interfaces (for all) or show interfaces fa 1/0/2

114
Q

What is a CRC

A

Frame check sequence, # of times the volume does not match between transmission and recession, if CRC’s match on both ends frame has not been modified

115
Q

What is a runt

A

frame runs too small and bad CRC

116
Q

What is a giant

A

frame runs too big and bad CRC

117
Q

What two modes don’t match up

A

full duplex and half duplex will not work

118
Q

How do you check a port’s VLAN membership

A

show vlan brief

119
Q

How do you add a port to a VLAN

A

switchport access vlan (number)

120
Q

How do you set the default gateway

A

ip default-gateway

121
Q

What are the three trunking configurations of Voice VLAN

A

Single VLAN Access Port: one VLAN shared with phone and computer VLAN, useful if phone is on computer or 3rd party
Multi VLAN Access Port: one VLAN but can support a second one if the second one is a voice VLAN
Cisco phone learns which VLAN it is in via CDP messages
Higher priority on voice
Trunk Port
Compatible with CDP and LLDP protocol

122
Q

What is NTP

A

Network Time Protocol, help interpret event logs, UDP port 123, stratum number of a time source indicates how accurate the time is

123
Q

Which of the following commands will disable SSH and Telnet connections on a switch?

A

transport input none

124
Q

How do you set NTP as master

A

in conf term ntp master (stratum number)

125
Q

How do you point a router to NTP server

A

from router config# ntp server (ip address)
clocktimezone (name) (hours)
To verify:
show ntp status

126
Q

What is NAT used for

A

Translating addresses from within a network to the global internet area of the network

127
Q

What’s the difference between global and local addresses

A

global addresses are publicly routable whereas local addresses are not routable

128
Q

What’s the difference between inside and outside addresses

A

Inside addresses mean that they are inside the network (private) while outside addresses are public addresses

129
Q

How do you config a router as a DHCP server

A

ip dhcp pool pc

130
Q

How do you see DHCP addresses

A

show ip dhcp binding

131
Q

How do you point a router to a DHCP server

A

ip helper-address (dhcp server ip)

132
Q

What’s the difference between coaxial and twisted pair cabling

A

Coaxial has conductor wrapped outside with insulator wrapped around in conductor wrapped in outside wire, twisted pair has individual pairs, sometimes shielded (wrapped around each pair) or unshielded

133
Q

What is RG 59 used for

A

carry video over short distances

134
Q

What is RG 58 used for

A

Carrying 10 Base 2 Ethernet

135
Q

What is category 3 used for

A

10 Base X connections

136
Q

What does the number before base refer to (ie 10 base 2, 100 base 2)

A

bits per second on ethernet speed

137
Q

What is a DB9 connection used for

A

Asynchronous connection and connection to modem

138
Q

What is a RJ 45 cable used for

A

Ethernet cables, Cat 5 and 6 Cables, used for ethernet connections

139
Q

What is RJ 11 used for

A

Telephone connections

140
Q

What is BNC used for

A

Used for data connections, 10 Base 2 Connections

141
Q

Which pins are crossed over for a ethernet cable

A

1,2 and 3,6

142
Q

How do you display a banner on a switch?

A

banner ?

143
Q

How do you remove a license

A

disable then reload 1. license boot module disable 2. license clear (license)

144
Q

How do you set MTU in a ping

A

ping enter set DF bit in IP header: yes sweep: yes

145
Q

How do you recover the password of a router

A
break into rommon then switch configuration register to 0x2142, reset router to log in without password 
copy startup config running config
// config register back 
config# config-register 0x2102
copy-running config startup config
146
Q

How do you configure an evaluation license

A

license boot machine chasis technology-package (license)

147
Q

What does ping send?

A

ping enter set DF bit in IP header: yes sweep: yes