Routing Pt 1 Flashcards

1
Q

What is Cisco Express Forwarding (CEF)?

A

The most recent and default Cisco IOS packet-forwarding mechanism that builds a Forwarding Information Base (FIB) and an adjacency table

CEF entries are changed based on network topology changes, not packet-triggered.

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2
Q

What does Fast Switching use to store next-hop information?

A

A fast-switching cache

Fast switching is an older packet forwarding mechanism that utilizes the CPU for unmatched packets.

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3
Q

What is Process Switching?

A

An older packet forwarding mechanism where each packet is processed individually by the CPU

This method matches the destination address with the routing table for every packet.

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4
Q

What are the three packet forwarding mechanisms supported by routers?

A
  • Process switching
  • Fast switching
  • Cisco Express Forwarding (CEF)
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5
Q

What is the primary responsibility of packet forwarding?

A

To encapsulate packets in the appropriate data link frame type for the outgoing interface.

For example, the data link
frame format for a serial link could be Point-to-Point (PPP) protocol, High-Level Data Link
Control (HDLC) protocol, or some other Layer 2 protocol.

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6
Q

What command is used to enter configuration mode on a router?

A

configure terminal

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7
Q

What command is used to display the IP interface status?

A

show ip interface brief

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8
Q

What does the letter ‘L’ signify in a routing table?

A

Identifies the address assigned to a router interface.

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9
Q

What are static routes commonly used for?

A
  • As a default route forwarding packets to a service provider
  • For routes outside the routing domain
  • Explicitly defining the path for a specific network
  • Routing between stub networks
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10
Q

What filtering command parameter displays the entire section that starts with the filtering expression?

A

section

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11
Q

What happens if there is no match in the routing table for a packet?

A

The packet will be dropped.

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12
Q

What is meant by ‘the longest match’ in routing?

A

The route in the routing table with the greatest number of far-left matching bits with the destination IP address.

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13
Q

Fill in the blank: The routing table contains a list of routes to known networks derived from directly connected networks, static routes, and _______.

A

dynamic routing protocols

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14
Q

True or False: Every router makes its forwarding decision based on the information in its routing table.

A

True

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15
Q

What does the code ‘C’ indicate in a routing table?

A

Identifies a directly connected network. Stands for Connected

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16
Q

What is the command to encrypt passwords in router configuration?

A

service password-encryption

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17
Q

What is the function of the command ‘ping’ in router verification?

A

To test connectivity to another device.

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18
Q

What does the command ‘show ip route’ display?

A

The contents of the IP routing table.

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19
Q

What are the two primary functions of a router?

A
  • Determine the best path to forward packets
  • Forward packets toward their destination
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20
Q

What is the significance of prefix length in routing?

A

It determines the number of far-left bits that must match for a successful route match.

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21
Q

In IPv4 longest match, which route entry would be chosen for the destination address 172.16.0.10?

A

172.16.0.0/26

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22
Q

In IPv6, which route entry matches the destination address 2001:db8:c000::99?

A

2001:db8:c000::/48 (longest match)

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23
Q

What command is used to copy the running configuration to the startup configuration?

A

copy running-config startup-config

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24
Q

What is the purpose of the command ‘banner motd’?

A

To display a message of the day upon login.

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25
Q

What does the command ‘no shutdown’ do in interface configuration?

A

Enables the interface.

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26
Q

What are the steps of the packet forwarding decision process?

A
  1. A data link frame with an encapsulated IP packet arrives on the ingress interface.
  2. The router examines the destination ip address in the packet header and consults the routing table
  3. Router finds the longest matching prefix in the routing table
  4. Router encapsulates the packet in a data link frame and forwards it out the egress interface. Destination could be a device connected to the network or a next hop router
  5. If there is no matching route entry, the packet is dropped
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27
Q

How does a router determine the next hop for a packet?

A

The router examines the destination IP address in the packet header and consults its IP routing table.

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28
Q

What does the longest matching prefix in the routing table signify?

A

It identifies the best matching route for the destination IP address.

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29
Q

What happens if there is no matching route entry in the routing table?

A

The packet is dropped.

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30
Q

What are directly connected networks in the context of routing?

A

Networks added to the routing table when a local interface is configured with an IP address and is active.

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31
Q

What are the two ways routers learn about remote networks?

A
  • Static routes
  • Dynamic routing protocols
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32
Q

What is a default route?

A

Specifies a next-hop router when the routing table does not contain a specific route matching the destination IP address.

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33
Q

What prefix length does a default route have?

A

/0

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34
Q

What is the purpose of the administrative distance in a routing table?

A

It identifies the trustworthiness of the route source.

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35
Q

What does a metric in a routing table represent?

A

The value assigned to reach the remote network. Also known as “the cost”

36
Q

What is the significance of the exit interface in a routing table?

A

It identifies the interface used for outgoing packets to reach their final destination.

37
Q

What is a stub network?

A

A network accessed by a single route, where the router has only one neighbor.

38
Q

What is equal cost load balancing?

A

When a router has multiple paths to a destination with equal cost metrics and forwards packets using both paths equally.

39
Q

Which dynamic routing protocol supports unequal cost load balancing?

A

EIGRP

40
Q

What status code denotes a directly connected network in the routing table?

A

C

41
Q

What does the status code ‘L’ represent in the routing table?

A

Local route

42
Q

What is the primary function of a router?

A

To determine the best path to forward packets based on the routing table.

43
Q

What is the longest match in routing?

A

The route in the routing table with the greatest number of far-left matching bits with the destination IP address.

44
Q

What is the difference between static and dynamic routing?

A
  • Static routing: Manually configured
  • Dynamic routing: Automatically adjusts to network changes
45
Q

What is the main purpose of dynamic routing protocols?

A

To discover remote networks and maintain up-to-date routing information.

46
Q

What metric does RIP use?

A

Hop count

47
Q

What metric does OSPF use?

A

Cost based on cumulative bandwidth.

48
Q

What is the metric calculation method used by EIGRP?

A

It considers the slowest bandwidth and delay values.

49
Q

What are the three main components of dynamic routing protocols?

A
  • Data structures
  • Routing protocol messages
  • Algorithms
50
Q

What is the role of algorithms in routing protocols?

A

To facilitate routing information and best path determination.

51
Q

What is the difference in configuration complexity between dynamic and static routing?

A
  • Dynamic routing: Independent of network size
  • Static routing: Increases with network size
52
Q

What are the two types of routing protocols based on the routing domain?

A
  • Interior Gateway Protocols (IGPs)
  • Exterior Gateway Protocol (EGP)
53
Q

What is the only EGP used for routing information exchange between organizations?

A

BGP (border gateway protocol)

54
Q

What does the term ‘best path’ refer to in routing?

A

The path with the lowest metric to reach a network.

55
Q

What is the significance of the route timestamp in a routing table?

A

It identifies how much time has passed since the route was learned.

56
Q

What is the command used to view the routing table in Cisco IOS?

A

show ip route

57
Q

What is the prefix length for IPv4 local routes?

A

/32

58
Q

What is the prefix length for IPv6 local routes?

A

/128

59
Q

Fill in the blank: The default route has an IPv4 route entry of ______.

A

0.0.0.0/0

60
Q

Fill in the blank: The routing table contains a list of routes known as ______.

A

networks (prefixes and prefix lengths)

61
Q

What is the purpose of dynamic routing protocols?

A

To automatically update and share information about the best path for data to travel through a network. Ensures data can still get the destination even if a router fails.

62
Q

What activities do dynamic routing protocols perform?

A

Network discovery and maintaining routing tables.

63
Q

What does an indented entry in an IPv4 routing table represent?

A

A child route.

64
Q

What is a parent route in an IPv4 routing table?

A

The classful network address shown above a child route.

65
Q

What is the administrative distance (AD) in routing protocols?

A

A measure of the trustworthiness of a route source.

66
Q

What is the administrative distance for a directly connected route?

A

0.

67
Q

What is the administrative distance for a static route?

A

1.

68
Q

What status code indicates a route learned by OSPF in a routing table?

A

O.

69
Q

Fill in the blank: The structure of an IPv4 routing table retains the _______ architecture.

A

classful.

70
Q

What is the format of a directly connected network in an IPv4 routing table?

A

Always indented as a child route.

71
Q

What is the administrative distance for OSPF?

A

110.

72
Q

True or False: The concept of classful addressing is part of IPv6.

A

False.

73
Q

How are IPv6 route entries formatted?

A

Every IPv6 route entry is formatted and aligned the same way.

74
Q

What does the ‘C’ code indicate in an IP routing table?

A

Connected route.

75
Q

What does the ‘L’ code represent in an IP routing table?

A

Local route.

76
Q

What does the ‘O’ code indicate in an IPv6 routing table?

A

OSPF Intra route.

77
Q

What routing protocol is used in the example to dynamically learn networks?

A

OSPF.

78
Q

What is the administrative distance for RIP?

A

120.

79
Q

Fill in the blank: The child route includes the route source and all the forwarding information such as the _______.

A

next-hop address.

80
Q

What is the administrative distance for External BGP?

A

20.

81
Q

What does the ‘D’ code signify in a routing table?

A

EIGRP route.

82
Q

What is indicated by the ‘OE2’ code in an IPv6 routing table?

A

OSPF External route.

83
Q

What does the ‘IA’ code mean in a routing table?

A

OSPF Inter area route.

84
Q

What is the administrative distance for Internal EIGRP?

A

90.

85
Q

What does the ‘B’ code represent in a routing table?

A

BGP route.