Reviewoswalcisco3

Cisco 3
Chapters 1 -10
Review Questions and Answer

Contents
Chapter 1	2
Scaling Networks:	2
Chapter 2	4
Scaling VLANs	4
Chapter 3	7
Spanning Tree Protocol (STP)	7
Chapter 4	9
EtherChannel and FHRP	9
Chapter 5	11
Dynamic Routing	11
Chapter 6	14
EIGRP	14
Chapter 7	18
Advanced EIGRP	18
Chapter 8	20
Single-Area OSPF	20
Chapter 9	24
Multi-Area OSPF	24
Chapter 10	26
Troubleshooting OSPF	26


Chapter 1


Scaling Networks:

1.	What are the 3 layers of the Hierarchical Design Model?

   Core Layer, Distribution Layer, Access Layer

2.	What is the collapsed Core?

   Distribution Layer is combined with the Access Layer

3.	What is a Failure Domain?
 areas of a network that are impacted when a critical device or      network service experiences problems

4.	What are some benefits of smaller failure domains?
  reduces the impact of a failure on company productivity  simplify troubleshooting

5.	What is Link Aggregation?
 increases the amount of bandwidth between devices by creating one    logical link made up of several physical links

6.	What is the port density of a switch?

   refers to the number of ports available on a single switch
24 ports, 48 ports, modular switch with up to 1000+ ports

7.	What is "Wire Speed" when referring to a switch?

    The processing capabilities of a switch are rated by how much data   the switch can process per second

8.	What is PoE?

  Power over Ethernet (carries electrical power)

9.	Multilayer switches are typically deployed in what layer or layers of the switched network?

    Deployed in the core and distribution layers of an organization’s   switched network


10.	When selecting routers, they can be classified into these 3 categories.

	    Branch – Highly available 24/	7
    Network Edge – High performance, high security, and reliable
    services. Connect campus, data center, and branch networks
	    Service provider routers

11.	What does EM mean when referring to Cisco IOS software releases?

  Extended Maintenance Release

12.	When managing devices, how does out-of-band and in-band compare?

 Out-of-band: requires direct connection to console or AUX port
     and Terminal Emulation client to access device

 In-Band:
requires, at least, one interface to be connected and
operational and use of Telnet, SSH, or HTTP to access device

Chapter 2



Scaling VLANs

1.	What does VTP stand for? What is its main purpose?

VTP: VLAN Trunking Protocol
 allows a network administrator to manage VLANs on a switch configured as a VTP server
2.	Where does VTP store VLAN configurations?
VTP stores VLAN configurations in a database called vlan.dat

3.	What is a VTP Domain? How are its boundaries defined?




4.	What are the three VTP modes?

VTP, Server, VTP Client, VTP Transparent

5.	What is the purpose of the configuration revision number?

The configuration revision number is used when determining whether a switch should keep its existing VLAN database, or overwrite it with the VTP update sent by another switch

6.	What are the main differences between a VTP Server and a VTP Client?

VTP Server:

Advertises the VTP domain VLAN information to other VTP-enabled
switches in the same VTP domain
Stores the VLAN information for the entire domain in NVRAM
Creates, deletes, or renames VLANs for the domain
Default VTP mode
●
●
●
●



VTP Client

●	Cannot create, change, or delete VLANs
●	Stores the VLAN information for the entire domain in RAM
●	Must be configured as VTP client


7.	What are the 5 typical steps to complete VTP configuration?

1.	Configure the VTP Server:
vtp mode server (default)
2.	Configure the VTP Domain Name and Password:
vtp domain domain-name (NULL by default) vtp password password
3.	Configure the VTP Clients vtp mode client vtp domain domain-name vtp password password
4.	Configure VLANs on the VTP Server
5.	Verify the VTP Clients have received the new VLAN information

8.	What is the Normal range for VLANs? and the Extended range? Who uses the     extended range?

Normal range VLANs are identified by a VLAN ID between 1 and 1005.
Extended range VLANs are identified by a VLAN ID between 1006 and
4094.

Used by service providers and large organizations to extend their
infrastructure to a greater number of customers

9.	What is the default VTP Domain for a switch? and the default  configuration revision number?
 switch is in VTP transparent mode and is in the no - management
domain state until the switch receives an advertisement for a
domain over a trunk link or you configure a management domain

Revision #: 0

10.	Which VLANs are automatically created and cannot be removed?

VLAN 1

11.	How do you configure an extended VLAN on a 2960 switch?
To configure an extended VLAN on a 2960 switch it must be set to VTP
transparent mode.


12.	What does DTP stand for? What is its main purpose? Who developed it?

Dynamic Trunking Protocol (DTP)
 to negotiate trunking with neighbor interfaces

Cisco proprietary protocol

13.	What two commands will enable trunking from a Cisco switch to a device that does not support DTP?
 switchport mode trunk, switchport nonegotiate

14.	What are the four trunking modes? Which combinations create trunks?



15. How does a router compares to a layer-3 switch, when considering forwarding
speed?



16.	What types of Layer 3 interfaces are supported by Catalyst multilayer switches?

Routed port, Switch virtual interface (SVI)
17.	What name is used to refer to a physical port that acts similarly to an interface on a router?

A routed port

18.	What command is used to configure a routed port?

no switchport

19.	What command allows you to see the configuration revision number?

Show vtp status
20.	What are trunk mode mismatches?
Trunk misconfiguration (both sides are configured DTP AUTO) Chapter 3


Spanning Tree Protocol (STP)

1.	What is the main purpose of STP?

Redundancy at OSI Layers 1 and 2

2.	What are two issues associated with redundancy?



MAC Database Instability
Broadcast Storms
Duplicate Unicast Frames


3.	What is a broadcast storm?

when there are so many broadcast frames caught in a Layer 2 loop
that all available bandwidth is consumed



4.	What are the 4 Port Roles associated to the STP algorithm (RSTP)?
Root Ports, Designated ports, Alternate and Backup ports,
Disabled ports

5.	What are the default (current)port costs for STP? And the original costs?




6.	What is a root port? And a designated port?

Root Port: Ports closest to the root bridge
Designated Ports: Non-root ports permitted to forward traffic
What is used as a reference point for all spanning tree calculations to
determine which redundant paths to block?
7.

8.	What switch becomes the root bridge?

The switch with the lowest BID will become the root bridge


9.	The root bridge automatically configures all of its switch ports in      the __________ role.

Designated Roles
10.	What command allows you to verify the port and internal root path cost to the root bridge

show spanning-tree

11.	The Bridge ID (BID) consists of which three separated fields?

Bridge priority, Extended system ID, MAC address

12.	What is the default value for the Bridge priority (bridge priority + extended system ID)?

32768

13.	What is the standard 802.1D?


14.	What are the five port states introduced by STP (PVST+)?

STP, PVST+, RSTP, Rapid PVST+, MSTP

15.	Which of the STP variants have been developed by Cisco?

PVST+, Rapid PVST+

16.	What is the name of the Cisco implementation of per-VLAN RSTP

Rapid PVST+

17.	What is an RSTP Edge Port?

is a switch port that is never intended to be connected to another
switch

18.	What is the purpose of the "spanning-tree vlan vlan-id root primary      global configuration command?

To ensure that the switch has the lowest bridge priority value

19.	How is Load Balancing done in a PVST+ network?
configure two or more root bridges for different sets of VLANs and make
use of redundant links

20.	What are the two methods of configuring the Bridge ID?  1:
spanning-tree vlan (vlan id)root primary
spanning-tree vlan (vlan id) priority (value)
2:

Chapter 4



EtherChannel and FHRP

1.	Why simply connecting 2 ports from switch 1 to 2 ports from switch 2 does not provide twice the BW?

by default, STP is enabled on Layer 2 devices such as switches. STP
will block redundant links to prevent routing loops

2.	What is port aggregation? Who developed EtherChannel?
Link aggregation combines a number of physical links between the switches to increase the overall bandwidth between two devices

Cisco

3.	What are the main restrictions on the implementation of EtherChannel?
EtherChannel interface types cannot be mixed. For example, Fast Ethernet and Gigabit Ethernet cannot be mixed in a port channel
4.	What are the 2 main protocols used to help configure EtherChannels?
Port Aggregation Protocol (PAgP)
Link Aggregation Control Protocol (LACP)

5.	Who developed PAgP? What are its 3 supported modes?

Cisco-proprietary protocol

Desirable, Auto, On

6.	Who developed LACP? What are its 3 supported modes?

Active. Passive, On

7.	When configuring EtherChannel with LACP, what are the two required steps?

Configure all bundle interfaces with the same speed and in the same
duplex mode

8.	Which commands allow to verify EtherChannel?
 show etherchannel summary


9.	What are some of the First Hop Redundancy Protocols?

ICMP Router Discovery Protocol (IRDP)
Hot Standby Router Protocol (HSRP)
HSRP for IPv6
Virtual Router Redundancy Protocol version 2 (VRRPv2)
VRRPv3
Gateway Load Balancing Protocol (GLBP) GLBP for IPv6
10.	What is the name of a Cisco-proprietary First Hop Redundancy Protocol that provides redundancy for IPv4

Hot Standby Router Protocol (HSRP)

11.	In HSRP, if the active router fails, what happens next?
the standby router automatically assumes the active router role without
requiring any configuration changes on hosts

12.	What command allows you to verify HSRP?

Show standby

13.	What is HSRP Priority?

is used to decide which router should be active and which router
should be standby

14.	What is HSRP Preemption?

enables the Hot Standby Router Protocol (HSRP) router with the highest
priority to immediately become the active router

15.	What multicast address is used by HSRPv1? And for version 2?

HSRPv1:
224.0.0.2
224.0.0.102 or FF02::66 for IPv6
HSRPv2:

Chapter 5



Dynamic Routing

1.	What is the purpose of dynamic routing protocols?

•	Discovery of remote networks
•	Maintaining up-to-date routing information
•	Choosing the best path to destination networks
•	Ability to find a new best path if the current path is no longer   available

2.	What are the different categories of routing protocols?


3.	What are some advantages and disadvantages of dynamic routing?

Advantages

•	Automatically share information about remote networks
•	Determine the best path to each network and add this information to
  their routing tables
•	Compared to static routing, dynamic routing protocols require less
  administrative overhead
•	Help the network administrator manage the time-consuming process of   configuring and maintaining static routes

Disadvantages

Dedicate part of a routers resources for protocol operation,
including CPU time and network link bandwidth
•


4.	What determines Interior vs Exterior Gateway protocols?

Interior: find network path information within an Autonomous System
Exterior: find network path information between different Autonomous   Systems

5.	Which protocols are Distance Vector routing protocols?

RIPv1, RIPv2, IGRP, EIGRP

6.	Which protocols are Link-State routing protocols?

OSPF, IS-IS

7.	Which protocols (category) send subnet mask information in their routing      updates, and which ones do not?

Send Information: • RIPv2, EIGRP, OSPF, and IS_IS
Don’t Send Information: • Only RIPv1 and IGRP

8.	What are some limitations of classfull routing protocols?

Cannot provide variable length subnet masks (VLSMs) and classless
interdomain routing (CIDR)
Create problems in discontiguous networks
•

•

9.	How Distance Vector and Link-State compare, in terms of Speed of      Convergence and in terms of Scalability?



10.	What defines a neighbor on Distance Vector Technologies?

•	Neighbors are routers that share a link and are configured to use   the same routing protocol.

11.	How frequently does RIP send periodic updates?
RIP sends routing-update messages at regular intervals (30 seconds)
and when the network topology changes

12.	What is the destination address of a RIPv1 update? and for RIPv2? and for      EIGRP?

RIPv1: 255.255.255.255
RIPv2: 224.0.0.9
EIGRP: 224.0.0.10

13.	Which distance vector protocols support Authentication?

RIPv2, EIGRP

14.	What is another name for the Link-State routing protocols?

SPF

15.	Who developed the SPF algorithm?

Edsger  Dijkstra’s

16.	What are the steps followed on the Link-State routing process?

•	Each router learns its own links and directly connected networks • Each router discovers its neighbors on directly connected networks   With Hello packets.
•	Each router builds a link-state packet containing the state of each    Directly connected link	.
•	Each router floods the LSP to all neighbors, who then store all LSPs   received in a database.

17.	When does a link-state router considers a neighbor as unreachable?

If a router stops receiving Hello packets from a neighbor, that neighbor is considered unreachable and the adjacency is broken

18.	When does the flooding of LSPs occur?

3rd step

19.	What is used for the construction of the SPF tree on a router?
Link-state database and the shortest path first (SPF) algorithm to
calculate the preferred path or shortest path to each network

20.	What are some advantages and disadvantages of the Link-State routing      protocols?

Advantages

•	Builds a complete topological map of the network to determine the
  Shortest path
•	Floods the LSP immediately to achieve faster converg	e
•	Only sends out LSP with new information when there is a change in the   topolog	y
•	Uses the concept of areas and allows for summarization.

Disadvantages

•	Requires additional memory to maintain the database and SPF tree
•	Requires more CPU processing t	o calculate the SPF algorithm and
  create a complete map of the topology
•	Requires more bandwidth during initial startups of the routers and
  could be an issue on unstable networks

Chapter 6



EIGRP

1.What is the name of the algorithm used on EIGRP? Diffusing Update Algorithm (DUAL)

2.	What does RTP means? Reliable Transport Protocol

3.	To what multicast address does EIGRP send packets?
Reserved IPv4 multicast address 224.0.0.10
Reserved IPv6 multicast address FF02::A

4.	What are the 5 types of EIGRP packets?
Hello, Update, Acknowledge, Query & Reply

5.	What the two Default Hello Intervals, and for what ranges of BW?
1.544 Mb/s @ 60s intervals	,

greater than 1.544 Mb/s @5s intervals

6.	How is defined the Hold Time?
How much time it will listen before dropping the “ping”

7.	Who assigns Autonomous System numbers?
ISP and other large institutions.

8.	What is the total number of AS numbers available (before and after 2007)? Before 2007 16bits, today it is 32bits.

9.	How do you enter EIGRP configuration "mode"?
router eigrp autonomous-system command

10.	What are the three ways to set a router-id?
1.The eigrp router-id ipv4-address command
2.The highest active IPv4 address of any of the loopback address
3.The highest active IPv4 address of any of the physical interface

11.	What are two "show" commands that will show the router-id of a router?
Show ip protocols
Show ip router
12.	How do we enable an interface on the router to send and receive EIGRP updates? network ipv4-network-address

13.	When would you use a wildcard mask on the EIGRP network statement? Wildcard mask is similar to the inverse of a subnet mask

14.	If you have the subnet 192.168.10.192/28, what wildcard mask would you use?
0.0.0.15

15.	If you have the subnet 172.18.0.0/18, what wildcard mask would you use? 0.0.191.255

16.	How do you prevent unnecessary routing update traffic going to the LANs (end users)? On what configuration-mode is this command executed?
Passive Interface, Router(config-router)# passive-interface interface-type interface-number


17.	What information is displayed by the "show ip eigrp neighbors" command? View the neighbor table • Verify neighbor adjacencies have been established

18.	Indicate 3 show commands that will show the AS number used during the configuration of an EIGRP domain.
Show ip protocols show ip eigrp topology
show ip eigrp neighbors

19.	What are the 4 factors (values) used as part of the EIGRP metric? Which two factors are used by default?
Composite Metric (Default)
Bandwidth Metric (Default)
Delay Metric
Load & Reliability

20.	What are the default values for the five K values used in the metric formula?
K1 bandwidth
K2 load
K3 delay
K4 reliability
K5 reliability

21.	What is the command used for changing the default K values? Router (config-router) metric weights (insert k to change)

22.	What command can be used to verify the K values? Show ip protocols

23.	What is the "default" bandwidth value set on a Serial interface? What command allows you to change the bandwidth of an interface?
1544 kb/s
Bandwidth (insert value of choice)

24.	What command allows you to verify some bandwidth changes you made? Show interfaces

25.	What are the lowest and the highest values for interface delays?
Lowest, 10 (GigabitEthernet)
Highest, 20000 (Multiple)

26.	What are the lowest and the highest values for interface load?
1/255 – 255/255

27.	Why are loop-free backup paths important for the DUAL algorithm?
loop-free path to the same network as the successor, and it satisfies the Feasibility Condition

28.	What is a successor? and a Feasible successor?
A successor is a neighboring router that is used for packet forwarding and is the least-cost route  to the	 destination network.
A feasible successor is a neighbor that has a loop-free path to the same network as the  successor, and it	 satisfies the Feasibility Condition

29.	What is the Feasibility Condition?
The feasibility condition (FC) is met when a neighbor's reported distance (RD) to a network is  less than	 the local router's feasible distance to the same destination network.

30.	Can you determine if a router is a Feasible Successor by using ONLY the "show ip route" command?
Yes

31.	Where (on what table) are ALL the successors and feasible successors listed? You can see it on the “show ip eigrp topology” table

32.	What command will show ALL paths (links) including those that are Successors or Feasible Successors, and those that ARE NOT Feasible Successors?
Show ip eigrp topplogy all-links

33.	How do you enable IPv6 routing?
ipv6 unicast-routing

34.	How do you configure the router-id in EIGRP for IPv6?
ipv6 route “eigrp autonomous-system
eigrp router-id
”
no shutdown

35.	How do you configure an interface or network to use EIGRP for IPv6?
Enter Interface line
ipv6 eigrp “autonomous-system
”

Chapter 7



Advanced EIGRP

1.	What effect does summarization has on the size of the routing table?
Summarization limits the number of routing advertisements and the size of the routing table

2.	What command disables automatic summarization? In what mode does the command run?
no auto-summary

3.	Prior to IOS 15.0, automatic summarization was enabled or disabled by default? Prior to IOS 15.0 (or 12.2-33) automatic summarization was enabled by default

4.	What is a problem that automatic summarization could create?
Automatic summarization could cause routing loops

5.	What "special" route can be used to prevent routing loops?
Propagating a Default Static Route

6.	How (what command) do we (use to) propagate a default route?
redistribute static

7.	On the output of a "show ip route", what does the source code EX means? It means it was learned manually from a static route.

8.	What command allows to configure the bandwidth percentage used by EIGRP on an interface?
	IPv4: ip bandwidth-percent eigrp as-number percent
	IPv6: ipv6 bandwidth-percent eigrp as-number percent
9.	How do you configure the Hello and Hold timers?
Hello	ip hello-interval eigrp as-number seconds ipv6 hello-interval eigrp as-number seconds
Hold	ip hold-time eigrp as-number seconds ipv6 hold-time eigrp as-number seconds

10.	How is "equal-cost" load balancing configured? and "unequal-cost"?
Equal Cost	maximum-paths value
Unequal Cost	variance

Chapter 8



Single-Area OSPF

1.	What are the main features of OSPF?
Classless
Fast converging
Secure
Effieceint
Scalable

2.	Name the 3 databases used by OSPF. What are the equivalent "table" names?
    What are the commands to display their contents?
	Adjacency Database – 	show ip ospf neighbor
	Link-State Database – 	show ip ospf database
	Forwarding Database – 	show ip route

3.	How is the SPF Tree created?
Using Link-State Operation and LSAs

4.	When is single-area OSPF useful?
Is useful for smaller networks with few routers.

5.	What happens if a link from area 1 (non-backbone) fails? Which areas will have to run the SPF algorithm?
Only routers within the area with the failure

6.	What are the 5 types of OSPF packets?
Hello
Database Description
Link-State Request
Link-State Update
Link-State Acknowledge

7.	To what IPv4 destination address are Hello packets sent?
224.0.0.5

8.	How frequently are Hello packets sent on Ethernet/P2P? and on NBMA?
Every 30 seconds

9.	How many times the Hello interval is the default Dead interval?
It is 4x the hello interval

10.	What is the formula to determine the number of adjacencies?
n(n-1)/2

11.	Does the OSPF process-id have to be the same on all routers on the same OSPF domain?
no

12.	What is the range of possible Process-ID values?
1-65535

13.	What are the 3 alternatives to define a Router ID (in order of importance)?
Router-Id
Highest loopback IP
Highest Active Interface IP
14.	What network command should be used to represent the subnet 10.1.0.0/19 ?  0.0.0.31

15.	What are benefits of using a passive-interface?
Efficient Bandwidth
Efficient Resources
Increased Security

16.	What is the default "reference bandwidth" used by Cisco to establish the OSPF metric? 10-8 or 100,000,000 bps

17.	If your max BW is Gigabit Ethernet, what command should be run to "adjust" the cost so that Gi0/0 will have a cost of 1 and Fa0/0 will have a cost of 10?
auto-cost reference-bandwidth

18.	What is the standard cost (no adjustment) to a remote network if the path includes:         FastEthernet - Serial T1 - Serial 64kbps - Ethernet
1637

19.	What 2 commands allow manually adjusting the cost of a link?
Bandwidth
Ip ospf cost

20.	What command allows you to verify adjacencies formed with neighbor routers? Show ip ospf neighbors

21.	What is the IPv6 address used to send routing information to ALL OSPF routers?
    And to the DR/BDR?
FF02::6
22.	How do you configure OSPFv3 on a network/interface?
Ipv6 unicast-routing
Enter ipv6 add
No shutdown

Ipv6 router ospf value
Router-id value

Enter interface
Ipv6 router ospf value area value

Chapter 9



Multi-Area OSPF


1.	What 3 problems arise from an OSPF single-area becoming too big?
Large routing table
Large link-state database
Frequent spf algorithm calculations

2.	What is the two-layer hierarchy used for implementing Multiarea OSPF? What are      the two types of areas?
Backbone (Area 0)
Regular (Any other area)

3.	An area should have no more than _____ routers. A router should not be in more than ____ areas. 50 routers, 3 areas

4.	What are the 4 types of routers?
Internal Routers
Backbone Routers
Area Border Routers
Autonomous System Boundary Routers

5.	What are Type 1 LSAs? Who generates them? Where do they circulate? Routers, OSPF, the route in the inter-area

6.	What are Type 2 LSAs? Who generates them? Where do they circulate?
Networks, OSPF, the route in the inter-area
7.	What are Type 5 LSAs? Who generates them? Where do they circulate? Autonomous System, OSPF external type 1 or type 2,

8.	What is an O IA routing table entry?
Summary of the lsas

9.	How do you configure an ABR router so that it "links" two areas?
When entering the “network” command, use the proper area of the interface connecting to it

10.	What are some helpful OSPF verification commands?
Show ip ospf neighbor
Show ip ospf interface
Show ip protocols
Show ip ospf interface brief
Show ip route ospf
Show ip ospf database

Chapter 10



Troubleshooting OSPF


1.	What are the 5 types of OSPF networkS?
Point-to-point
Broadcast Multiaccess
Non-broadcast multi-access
Point-to-multipoint
Virtual links

2.	What are the 2 main challenges associated to multiaccess networks?
Creation of multiple adjacencies
Extensive flooding of LSAs

3.	What is the name assigned to non-DR/non-BDR routers?
DROTHERS

4.	Where are DR/BDR elections necessary?
DR/BDR Elections only necessary on multiaccess networks.

5.	DROTHERS only send their LSAs to the ____ and ____ using the IPv4 address _________.
DR & BDR using the 224.0.0.6 address.

6.	Which router, in a multiaccess network, floods the network with LSAs?
DR


7.	What command allows to verify the DR/BDR roles?
	Show ip ospf interface interface

8.	What are the 4 states of neighbors in a multiaccess network? And what is the      state on a point-to-point network?
Multiaccess	FULL/DROTHER	Point-to-point	FULL
	FULL/DR		2WAY
FULL/BDR
2-WAY/DROTHER

9.	What are the factors that influence the DR/BDR election process, in order of importance?
The router with the highest interface priority is elected as the DR.
The router with the second highest interface priority is elected as the BDR.
Priority can be configured between 0-255, with default of 1 (Priority of 0 - router cannot become  the	 DR).
If interface priorities are equal, then the router with highest router ID is elected DR and second  highest	 the BDR

10.	What are the range of possible values for the Interface Priority? What does a priority     of 0 means?
1 – 255, 0 means the router will never be a DR/BDR

11.	When a DR is not anymore a DR? Indicate the 3 possible events.
There is then a new BDR election and the DROTHER with the higher priority or router ID is  elected as the	 new BDR.
Re-Joins network
Fails
12.	How do you change the priority of an interface?
	ip ospf priority value	 (OSPFv2 interface command)
	ipv6 ospf priority value	 (OSPFv3 interface command)
13.	What commands (TWO) allow you to verify the priority of an interface?
	Show ip ospf interface interface
Show ip ospf neighbor

14.	How do you propagate a default static route in OSPFv2?
Default-information originate

15.	What are the default Hello and Dead intervals in OSPF?
Hello 	10s
Dead	40s