interview ccnp

8/2/2019 Interview CCNP

http://slidepdf.com/reader/full/interview-ccnp 1/47

Basic Q & A ( switching )

1. What is multilayer switching (MLS)?

** MLS forwards traffic using information from Layer 2, Layer 3, and Layer 4all in hardware

at wire speed.

2.What is a collision domain, and where does it exist in a switched LAN?

** A collision domain is a network segment where shared media access is supported.

Devices on the shared media must compete for access when transmitting data. In a

switched network, the collision domain is restricted to a single switch port and does not

extend across the switch.

3. What is a broadcast domain, and where does it exist in a switched LAN?

** A broadcast domain is the extent of a network where broadcast frames propagate.

Basically, a broadcast domain covers an area where Layer 2 devices are located and

terminates at the boundary of a Layer 3 device. In a switched network, the broadcast

domain extends to all switch ports assigned to a common VLAN. This is because a switch

forwards broadcasts out all available ports in a VLAN.

4. What is a VLAN, and why is it used?

** A virtual LAN (VLAN) is a group of switch ports that communicate as if they were

attached to a single shared-media LAN segment. VLANs can extend across buildings or

backbones, as long as the VLAN is connected end to end through trunking or physical

connections. A VLAN is a broadcast domain. VLANs segment networks for ease of

management and better performance.



5. At what OSI layers do devices in the distribution layer usually operate?

** Layers 2, 3, and 4

6. What is network segmentation? When is it necessary, and how is it done in a campus

network design?

** Segmentation is the process of dividing a LAN into smaller, discrete collision domains. If a

large percentage of collisions is observed on a LAN, segmentation is appropriate. In a campus

network design, segmentation occurs at each switch port. A similar form of segmentation

involves reducing the size of broadcast domains. Placing Layer 3 devices in the distribution and

core layers terminates the broadcast domains at those layer boundaries.

EIGRP Q & A

1: Is EIGRP a distance vector or a link state routing protocol?

*** EIGRP is a Hybrid routing protocol,it have features of both distance vector and link state routing

protocol.

2: What is the maximum configured bandwidth EIGRP will use on a link? Can this

percentage be changed?

*** By default, EIGRP uses no more than 50% of the link's bandwidth, based on the bandwidth

configured on the router's interface. This percentage to be changed with the command ip

bandwidth-percent eigrp.

3: How do EIGRP and IGRP differ in the way they calculate the composite metric?

*** EIGRP and IGRP use the same formula to calculate their composite metrics, but EIGRP scales

the metric by a factor of 256.



4: In the context of EIGRP, what does the term reliable delivery mean? Which two methods

ensure reliable delivery of EIGRP packets?

*** Reliable delivery means EIGRP packets are guaranteed to be delivered, and they are delivered

in order. RTP uses a reliable multicast, in which received packets are acknowledged, to guarantee

delivery; sequence numbers are used to ensure that they are delivered in order.

5: Which mechanism ensures that a router is accepting the most recent route entry?

*** Sequence numbers ensure that a router is receiving the most recent route entry.

6: What is the multicast IP address used by EIGRP?

*** EIGRP uses the multicast address 224.0.0.10.

7: At what interval, by default, are EIGRP Hello packets sent?

*** The default EIGRP Hello interval is 5 seconds, except on some slow-speed (T1 and below)

interfaces, where the default is 60 seconds.

8: What is the default hold time?

*** The EIGRP default hold time is three times the Hello interval.

9: What is the difference between the neighbor table and the topology table?

*** The neighbor table stores information about EIGRP-speaking neighbors; the topology table lists

all known routes that have feasible successors.



10: What is the feasibility condition?

*** The feasibility condition is the rule by which feasible successors are chosen for a destination.

The feasibility condition is satisfied if a neighbor's advertised distance to a destination is lower than

the receiving router's feasible distance to the destination. In other words, a router's neighbor meets

the feasibility condition if the neighbor is metrically closer to the destination than the router. Another

way to describe this is that the neighbor is "downstream" relative to the destination.

Basics Q & A {Switching}

1) What is unicast and how does it work?

** Unicast is a one-to-one transmission method. A single frame is sent from the source to a

destination on a network. When this frame is received by the switch, the frame is sent on to

the network, and the network passes the frame to its destination from the source to a

specific destination on a network.

2) What is multicast and how does it work?

** Multicast is a one-to-many transmission method. A single frame is sent from the source

to multiple destinations on a network using a multicast address. When this frame is

received by the switch, the frame is sent on to the network and the network passes the

frame to its intended destination group.

3: What is broadcast and how does it work?

** Broadcast is a one-to-all transmission method. A single frame is sent from the source to

a destination on a network using a multicast address. When this frame is received by the

switch, the frame is sent on to the network. The network passes the frame to all nodes in

the destination network from the source to an unknown destination on a network using a

broadcast address. When the switch receives this frame, the frame is sent on to all the

networks, and the networks pass the frame on to all the nodes. If it reaches a router, the

broadcast frame is dropped.



4: What is fragmentation?

** Fragmentation in a network is the breaking down of a data packet into smaller pieces to

accommodate the maximum transmission unit (MTU) of the network.

5:What is MTU? What's the MTU for traditional Ethernet?

** MTU is the acronym for maximum transmission unit and is the largest frame size that can be

transmitted over a network. Messages longer than the MTU must be divided into smaller

frames. The network layer (Layer 3) protocol determines the MTU from the data link layer

(Layer 2) protocol and fragments the messages into the appropriate frame size, making the

frames available to the lower layer for transmission without further fragmentation. The MTU for

Ethernet is 1518 bytes.

6: What is a MAC address?

** A MAC address is the physical address of a network device and is 48 bits (6 bytes) long.

MAC addresses are also known as physical addresses or hardware addresses.

7) What is the difference between a runt and a giant, specific to traditional Ethernet?

** In Ethernet a runt is a frame that is less than 64 bytes in length, and a giant is a frame that is

greater than 1518 bytes in length. Giants are frames that are greater than the MTU used, which

might not always be 1518 bytes.

8: What is the difference between store-and-forward and cut-through switching?

** Cut-through switching examines just the frame header, determining the output switch port

through which the frame will be forwarded. Store-and-forward examines the entire frame,

header and data payload, for errors. If the frame is error free, it is forwarded out its destination

switch port interface. If the frame has errors, the switch drops the frame from its buffers. This is

also known as discarding the frame to the bit bucket.



9: What is the difference between Layer 2 switching and Layer 3 switching?

* * Layer 2 switches make their forwarding decisions based on the Layer 2 (data link) address,

such as the MAC address. Layer 3 switches make their forwarding decisions based on the

Layer 3 (network) address.

10: What is the difference between Layer 3 switching and routing?

** The difference between Layer 3 switching and routing is that Layer 3 switches have

hardware to pass data traffic as fast as Layer 2 switches. However, Layer 3 switches make

decisions regarding how to transmit traffic at Layer 3 in the same way as a router. A Layer 3

switch cannot use WAN circuits or use routing protocols; a router is still required for these

functions.

OSI

(ISO) International organization for standardization

Iso has designed a reference model called osi reference model(open system interconnection).

It has 7 layers. It says thatAny n/w for comunication needs 7 layers

7.Application layer:

The user uses application layer to send the data. The protocols@ this layer are ftp,http,smtp(e-

mail) telenet etc.

6.Presentation layer:

Presentation layer takes the data from application layer and presenting different formats for

securing reason. The services offered @This layer areCompression – decompressionCoding –

decodingEncryption – decryption



5. Session layer:

Establishing the session or the conectivity n/w n/w 1 & n/w 2 is doneBy the session layer.It 1.

Establishes a session2. maintains it &3. Terminates it b/w the application

4. Transport layer:

End-end connectivity during a session b/w two application is doneBy the transport layer. It also

decides the type of connection like tcp or udp i.e. connection oriented or connection

less.Services:SequencingFlow ctrl, error detection & correctionTransport layer info + data is called

segment

3. Netwrok layer :

Logical addressing is done at the network layer i.e. source address & destination address are

attached to the data.Protocols @network layerRouted protocols routing protocolsEg: ip,ipx eg:

rip,igrp,ospfRouted protocols: they always carry the data along with them Routing protocol: they

identify the path for routed protocol tocarry the dataAt this layer routers & layer 3 switches forms

packets.

2.Data link layer:

It has two Sub layersa)MAC{Media access control } b) LLC {logical link control framing of data}Ip

address is lik the pincode & MAC address is like house number.Here layer2 switches are used.Wab

protocols used at this layer are PPP,HDLC,FP,X.25 etc.Here error checking CRC bits are added to

the packetsDLL info+ packets --> frames

1. physical layer:

Takes care of physical connectivity i.e connector,cable etc. hereFrames are converted to bits (1’s &

0’s).The devices like hubs, repeaters,cables & connectors are used atthis layer



Important Networking Q & A

1: What information must be stored in the route table?

** At a minimum, each entry of the routing table must include a destination address and the

address of a next-hop router or an indication that the destination address is directly connected.

2: What does it mean when a route table says that an address is variably subnetted?

**Variably subnetted means that the router knows of more than one subnet mask for subnets of the

same major IP address.

3: What are discontiguous subnets?

** Discontiguous subnets are two or more subnets of a major IP network address that are

separated by a different major IP address.

4: What command is used to examine the route table in a Cisco router?

** show ip route is used to examine the routing table of a Cisco router.

5: What are the two bracketed numbers associated with the non-directly connected routes in

the route table?

**The first bracketed number is the administrative distance of the routing protocol by which the

route was learned. The second number is the metric of the route.



6: When static routes are configured to reference an exit interface instead of a next-hop

address, in what way will the route table be different?

**When a static route is configured to reference an exit interface instead of a next-hop address, the

destination address will be entered into the routing table as directly connected.

7: What is a summary route? In the context of static routing, how are summary routes

useful?

** A summary route is a single route entry that points to multiple subnets or major IP addresses. In

the context of static routes, summary routes can reduce the number of static routes that must be

configured.

8: What is an administrative distance?

** An administrative distance is a rating of preference for a routing protocol or a static route. Every

routing protocol and every static route has an administrative distance associated with it. When a

router learns of a destination via more than one routing protocol or static route, it will use the route

with the lowest administrative distance.

9: What is a floating static route?

** A floating static route is an alternative route to a destination. The administrative distance is set

high enough that the floating static route is used only if a more-preferred route becomes

unavailable.

10: What is the difference between equal-cost and unequal-cost load sharing?

**Equal-cost load sharing distributes traffic equally among multiple paths with equal metrics.

Unequal-cost load sharing distributes packets among multiple paths with different metrics. The

traffic will be distributed inversely proportional to the cost of the routes.



OSPF Q & A

1: What is an OSPF neighbor?

*** From the perspective of an OSPF router, a neighbor is another OSPF router that is attached to

one of the first router's directly connected links.

2: What is an OSPF adjacency?

***An OSPF adjacency is a conceptual link to a neighbor over which LSAs can be sent.

3: What is an LSA? How does an LSA differ from an OSPF Update packet?

***A router originates a link state advertisement to describe one or more destinations. An OSPF

Update packet transports LSAs from one neighbor to another. Although LSAs are flooded

throughout an area or OSPF domain, Update packets never leave a data link.

4: What is a link state database? What is link state database synchronization?

***The link state database is where a router stores all the OSPF LSAs it knows of, including its own.

Database synchronization is the process of ensuring that all routers within an area have identical

link state databases.

5: What is the default HelloInterval?

***The default OSPF HelloInterval is 10 seconds.

6: What is the default RouterDeadInterval?

***The default RouterDeadInterval is four times the HelloInterval.



7: What is a Router ID? How is a Router ID determined?

***A Router ID is an address by which an OSPF router identifies itself. It is either the numerically

highest IP address of all the router's loopback interfaces, or if no loopback interfaces are

configured, it is the numerically highest IP address of all the router's LAN interfaces.

8: What is an area?

***An area is an OSPF sub-domain, within which all routers have an identical link state database.

9: What is the significance of area 0?

***Area 0 is the backbone area. All other areas must send their inter-area traffic through the

backbone.

10: What is MaxAge?

***MaxAge, 1 hour, is the age at which an LSA is considered to be obsolete.

Routing Information Protocol Version 2

1: Which three fields are new to the RIPv2 message format?

*** The Route Tag field, the Subnet Mask field, and the Next Hop field are RIPv2 extensions that do

not exist in RIPv1 messages. The basic format of the RIP message remains unchanged between

the two versions; version 2 merely uses fields that are unused in version 1.

2: Besides the extensions defined by the three fields of question 1, what are the other twomajor changes from RIPv1?

***In addition to the functions that use the new fields, RIPv2 supports authentication and multicast

updates.



3: What is the multicast address used by RIPv2? What is the advantage of multicasting

messages over broadcasting them?

***RIPv2 uses the multicast address 224.0.0.9. Multicasting of routing messages is better than

broadcasting because hosts and non-RIPv2 routers will ignore the multicast messages .

4: What is the purpose of the Route Tag field in the RIPv2 message?

*** When another routing protocol uses the RIPv2 domain as a transit domain, the protocol external

to RIPv2 can use the Route Tag field to communicate information to its peers on the other side of

the RIPv2 domain.

5: What is the purpose of the Next Hop field?

*** The Next Hop field is used to inform other routers of a next-hop address on the same

multiaccess network that is metrically closer to the destination than the originating router.

6: What is the UDP port number used by RIPv2?

***RIPv2 uses the same UDP port number as RIPv1, port number 520.

7: Which one feature must a routing protocol have to be a classless routing protocol?

***A classless routing protocol does not consider the major network address in its route lookups,

but just looks for the longest match.

8: Which one feature must a routing protocol have to use VLSM?

*** To support VLSM, a routing protocol must be able to include the subnet mask of each

destination address in its updates.



9: Which two types of authentication are available with Cisco's RIPv2? Are they both defined

in RFC 1723?

*** Cisco's implementation of RIPv2 supports clear-text authentication and MD5 authentication.

Only clear-text authentication is defined in RFC 1723.

Labels: RIP V2

Routing Information Protocol

1:What port does RIP use?

* RIP uses UDP port 520.

2:What metric does RIP use? How is the metric used to indicate an unreachable network?

* RIP uses a hop count metric. An unreachable network is indicated by setting the hop count to 16,

which RIP interprets as an infinite distance.

3:What is the update period for RIP?

* RIP sends periodic updates every 30 seconds minus a small random variable to prevent the

updates of neighboring routers from becoming synchronized.

4:How many updates must be missed before a route entry will be marked as unreachable?

* A route entry is marked as unreachable if six updates are missed.

5:What is the purpose of the garbage collection timer?

* The garbage collection timer, or flush timer, is set when a route is declared unreachable. When

the timer expires, the route is flushed from the route table. This process allows an unreachable

route to remain in the routing table long enough for neighbors to be notified of its status.

Labels: RIP

http://cinemas4u.blogspot.com/search/label/RIP%20V2


http://cinemas4u.blogspot.com/search/label/RIP






V-LAN

1. What is a VLAN? When is it used?

Answer: A VLAN is a group of devices on the same broadcast domain, such as a logical subnet or

segment. VLANs can span switch ports, switches within a switch block, or closets and buildings.

VLANs group users and devices into common workgroups across geographical areas. VLANs help

provide segmentation, security, and problem isolation.

2. When a VLAN is configured on a Catalyst switch port, in how much of the campus

network will the VLAN number be unique and significant?

Answer: The VLAN number will be significant in the local switch. If trunking is enabled, the VLAN

number will be significant across the entire trunking domain. In other words, the VLAN will be

transported to every switch that has a trunk link supporting that VLAN.

3. Name two types of VLANs in terms of spanning areas of the campus network.

Answer: Local VLAN

End-to-end VLAN

4. What switch commands configure Fast Ethernet port 4/11 for VLAN 2?

Answer: interface fastethernet 4/11

switchport mode access

switchport access vlan 2

5. Generally, what must be configured (both switch and end-user device) for a port-based

VLAN?

Answer: The switch port
























6. What is the default VLAN on all ports of a Catalyst switch?

Answer: VLAN 1

7. What is a trunk link?

Answer: A trunk link is a connection between two switches that transports traffic from multiple

VLANs. Each frame is identified with its source VLAN during its trip across the trunk link.

8. What methods of Ethernet VLAN frame identification can be used on a Catalyst switch

trunk?

Answer: 802.1Q

ISL

9. What is the difference between the two trunking methods? How many bytes are added to

trunked frames for VLAN identification in each method?

Answer: ISL uses encapsulation and adds a 26-byte header and a 4-byte trailer. 802.1Q adds a 4-

byte tag field within existing frames, without encapsulation.

10. What is the purpose of the Dynamic Trunking Protocol (DTP)?

Answer: DTP allows negotiation of a common trunking method between endpoints of a trunk link.

11. What commands are needed to configure a Catalyst switch trunk port Gigabit 3/1 to

transport only VLANs 100, 200 through 205, and 300 using IEEE 802.1Q? (Assume that

trunking is enabled and active on the port already. Also assume that the interface gigabit 3/1

command already has been entered.)

Answer: switchport trunk allowed vlan 100, 200-205, 300























12. Two neighboring switch trunk ports are set to the auto mode with ISL trunking

encapsulation mode. What will the resulting trunk mode become?

Answer: Trunking will not be established. Both switches are in the passive auto state and are

waiting to be asked to start the trunking mode. The link will remain an access link on both switches.

13. Complete the following command to configure the switch port to use DTP to actively ask

the other end to become a trunk:

switchport mode _________________

Answer: switchport mode dynamic desirable

14. Which command can set the native VLAN of a trunk port to VLAN 100 after the interface

has been selected?

Answer: switchport trunk native vlan 100

15. What command can configure a trunk port to stop sending and receiving DTP packets

completely?

Answer: switchport nonegotiate

16. What command can be used on a Catalyst switch to verify exactly what VLANs will be

transported over trunk link gigabitethernet 4/4?

Answer: show interface gigabitethernet 4/4 switchport

or

show interface gigabitethernet 4/4 switchport trunk






















17. Suppose that a switch port is configured with the following commands. A PC with a

nontrunking NIC card then is connected to that port. What, if any, traffic will the PC

successfully send and receive?

interface fastethernet 0/12

switchport trunk encapsulation dot1q

switchport trunk native vlan 10

switchport trunk allowed vlan 1-1005

switchport mode trunk

Answer: The PC expects only a single network connection, using a single VLAN. In other words,

the PC can't participate in any form of trunking. Only untagged or unencapsulated frames will be

understood. Recall that an 802.1Q trunk's native VLAN is the only VLAN that has untagged frames.

Therefore, the PC will be capable of exchanging frames only on VLAN 10, the native VLAN.

Layer 3 Switching

1. What might you need to implement interVLAN routing?

** One or more Layer 3 interfaces

One or more SVIs

Static routes

A dynamic routing protocol

2. Can interVLAN routing be performed over a single trunk link?

** Yes. Packets can be forwarded between the VLANs carried over the trunk.

3. To configure an SVI, what commands are needed?

























** First, make sure the VLAN is defined on the switch.

interface vlan vlan-id

ip address ip-address mask

no shutdown

4. What command can verify the VLAN assignments on a Layer 2 port?

** show interface type mod/num switchport

or

show interface status

5. A switch has the following interface configurations in its running configuration:

interface fastethernet 0/1

switchport access vlan 5

!

interface vlan 5

ip address 192.168.10.1 255.255.255.0

no shutdown

What is necessary for packets to get from the FastEthernet interface to the VLAN 5 SVI?

Answer: Nothing. Both are assigned to VLAN 5, so normal Layer 2 transparent bridging will take

care of all forwarding between the two.

6. What is the source of FIB information?























** The routing table, as computed by the Layer 3 engine portion of a switch.

7. How often is the FIB updated?

** As needed. It is downloaded or updated dynamically by the Layer 3 engine whenever the routing

topology changes or an ARP entry changes.

8. What is meant by the term "CEF punt"?

** A packet can't be forwarded or switched by CEF directly because it needs further processing.

The packet is "punted" to the Layer 3 engine, effectively bypassing CEF for a more involved

resolution.

9. What happens to the FIB when distributed CEF (dCEF) is used?

** It is simply replicated to each of the independent CEF engines. The FIB itself remains intact so

that each engine receives a duplicate copy.

10. What happens during a "CEF glean" process?

** The MAC address (ARP reply) for a next-hop FIB entry is not yet known. The Layer 3 engine

must generate an ARP request and wait for a reply before CEF forwarding can continue to that

destination.

11. What does a multilayer switch do to the IP TTL value just before a packet is forwarded?

** The TTL is decremented by one, as if a router had forwarded the packet.

12. What is fallback bridging?

** On switch platforms that cannot multilayer-switch (route) all routable protocols, those protocols

can be bridged transparently between VLANs instead.

13. Is it possible for an SVI to go down? If so, for what reasons?
























** Yes. The SVI can be shut down administratively with the shutdown command, as with any other

interface. Also, if the VLAN associated with the SVI is not defined or active, the SVI will appear to

be down.

Dynamic Routing Protocols

1: What is a routing protocol?

* A routing protocol is a "language" that routers speak to each other to share information about

network destinations.

2: What basic procedures should a routing algorithm perform?

* At a minimum, a routing protocol should define procedures for:Passing reachability information

about networks to other routersReceiving reachability information from other routersDetermining

optimal routes based on the reachability information it has and for recording this information in a

route tableReacting to, compensating for, and advertising topology changes in an internetwork

3: Why do routing protocols use metrics?

**A route metric, also called a route cost or a route distance, is used to determine the best path to a

destination. Best is defined by the type of metric used.

4: What is convergence time?

* Convergence time is the time a group of routers take to complete the exchange of routing

information.

5: What is load balancing? Name four different types of load balancing.






















* Load balancing is the process of sending packets over multiple paths to the same

destination.Four types of load balancing are:

a) Equal cost, per packet

b) Equal cost, per destination

c) Unequal cost, per packet

d) Unequal cost, per destination

RIP , Q & A part ----II

6: Why is a random timer associated with triggered updates? What is the range of this

timer?

* The random timer, whose range is 1 to 5 seconds, prevents a "storm" of triggered updates during

a topology change.

7: What is the difference between a RIP Request message and a RIP Response message?

* A Request message asks a router for an update. A Response message is an update.

8: Which two types of Request messages does RIP use?

* A Request message may either ask for a full update or in some special cases it may ask for

specific routes.

9: Under what circumstances will a RIP response be sent?

* A Response is sent when the update timer expires, or upon reception of a Request message.

10: Why does RIP hide subnets at major network boundaries?






















** RIP updates do not include the subnet mask of the destination address, so a RIP router depends

on the subnet masks of its own interfaces to determine how an attached major network address is

subnetted. If a router does not have an attachment to a particular major network address, it has no

way to know how that major network is subnetted. Therefore, no subnets of a major network

address can be advertised into another major network

Static Routing

1: What information must be stored in the route table?

* At a minimum, each entry of the routing table must include a destination address and the address

of a next-hop router or an indication that the destination address is directly connected.

2: What does it mean when a route table says that an address is variably subnetted?

* Variably subnetted means that the router knows of more than one subnet mask for subnets of the

same major IP address..

3: What are discontiguous subnets?

* Discontiguous subnets are two or more subnets of a major IP network address that are separated

by a different major IP address.

4: What command is used to examine the route table in a Cisco router?

* show ip route is used to examine the routing table of a Cisco router.

5: What are the two bracketed numbers associated with the non-directly connected routes in

the route table?















* The first bracketed number is the administrative distance of the routing protocol by which the

route was learned. The second number is the metric of the route.

Dynamic Routing Protocols Part- II

6: What is a distance vector routing protocol?

* A distance vector protocol is a routing protocol in which each router calculates routes based on

the routes of its neighbors and then passes its routes to other neighbors.

7: Name several problems associated with distance vector protocols.

* Several problems associated with distance vector protocols are:

-> A susceptibility to incorrect routing information because of its dependence on neighbors for

correct information

-> Slow convergence

-> Route loops

-> Counting to infinity

8: What are neighbors?

* Neighbors are routers connected to the same data link.

9: What is the purpose of route invalidation timers?

* Route invalidation timers delete routes from a route table if they exceed a certain age.

10: Explain the difference between simple split horizon and split horizon with poisoned

reverse.

* Simple split horizon does not send route information back to the source of the route information.



Split horizon with poisoned reverse sends the information back to the source but sets the metric to

unreachable.

OSPF Q & A in CCNP

1: Which command in OSPF shows the network LSA information?

** The command show ip ospf [process-id area-id] database network displays the network link-state

information.

2: What command would you use to create a totally stubby area?

** The command area area-id stub no-summary will create a totally stubby area. This is a

subcommand to the router ospf process-id command. It is necessary only on the ABR, but all the

other routers in the area must be configured as stub routers.

3: What is a virtual link, and what command would you use to create it?

** A virtual link is a link that creates a tunnel through an area to the backbone (Area 0). This allows

an area that cannot connect directly to the backbone to do so virtually. The command to create the

link is area area-id virtual-link router-id. Note that the area-id that is supplied is that of the transit

area, and the router-id is that of the router at the other end of the link. The command needs to be

configured at both ends of the tunnel.

4: Where would you issue the command to summarize IP subnets? State the command that

is used.

** Summarization is done at area boundaries. The command to start summarization is the area

range command, with the syntax area area-id range address mask. To summarize external routes,

use the summary-address command on the ASBRs.

5: How would you summarize external routes before injecting them into the OSPF domain?

** The command summary-address address mask is the command that you would use.



6: When is a virtual link used?

** A virtual link is used when an area is not directly attached to the backbone area (Area 0). This

may be due to poor design and a lack of understanding about the operation of OSPF, or it may be

due to a link failure. The most common cause of an area separating from the backbone is link

failure, which can also cause the backbone to be segmented. The virtual link is used in these

instances to join the two backbone areas together. Segmented backbone areas might also be the

result of two companies merging.

7: Give the command for defining the cost of a default route propagated into an area.

** The command to define the cost of a default route propagated into another area is area area-id

default-cost cost.

8: Give an example of when it would be appropriate to define a default cost.

** It is appropriate to define a default cost for the default route when a stub area has more than one

ABR. This command allows the ABR or exit point for the area to be determined by the network

administrator. If this link or the ABR fails, the other ABR will become the exit point for the area.

9: On which router is the area default cost defined?

** The default cost for the default route is defined on the ABR. The ABR will then automatically

generate and advertise the route cost along with the default route.

10: Give the command to configure a stub area and state on which router it is configured.

** The command syntax to configure a stub area is area area-id stub. This command is configured

on the ABR connecting to the area and on all the routers within the area. Once the configuration is

completed, the Hellos are generated with the E bit set to 0. All routers in the area will only form

adjacencies with other routers that have the E bit set.



11: What is the purpose of the area range command, and why is it configured on the ABR?

** The area range command is configured on an ABR because it dictates the networks that will be

advertised out of the area. It is used to consolidate and summarize the routes at an area boundary.

12: Give the commands to configure a router to place subnets 144.111.248.0 through to

144.111.255.0 in Area 1 and to put all other interfaces into Area 0.

** The commands are as follows:

network 144.111.248.0 0.0.7.255 area 1

network 0.0.0.0 255.255.255.255 area 0

13: Give the syntax to summarize the subnets 144.111.248.0 to 144.111.254.255 into another

autonomous system.

** The syntax is as follows:

summary-address 144.111.248.0 255.255.248.0

14: Explain briefly the difference between the area range command and the summary-

address command.

** The area range command is used to summarize networks between areas and is configured on

the ABR. The summary-address command is used to summarize networks between autonomous

systems and is configured on the ASBR.



15: Explain the following syntax and what it will achieve: area 1 stub no-summary.

** The command area 1 stub no-summary creates a totally stubby area. The number after the word

area indicates the area that is being defined as a totally stubby area. This is necessary because the

router might be an ABR with connections to many areas. Once this command is issued, it prevents

summarized and external routes from being propagated by the ABR into the area. To reach the

networks and hosts outside the area, routers must use the default route advertised by the ABR into

the area.

16: Why would you configure the routing process to log adjacency changes as opposed to

turning on debug for the same trigger?

** The reason to configure the router process to log adjacency changes to syslog as opposed to

running debug is an issue of resources. It takes fewer router and administrator resources to report

on a change of state as it happens than to have the debugger running constantly. The debug

process has the highest priority and thus everything waits for it.

17: Give some of the common reasons that neighbors fail to form an adjacency.

** Many OSPF problems stem from adjacency problems that propagate throughout the network.

Many problems are often traced back to neighbor discrepancies.

If a router configured for OSPF routing is not seeing an OSPF neighbor on an attached network, do

the following:

- Make sure that both routers are configured with the same IP mask, MTU, Interface Hello timer,

OSPF Hello interval, and OSPF dead interval.

- Make sure that both neighbors are part of the same area and area type.

- Use the debug and show commands to trace the problem.



18: When configuring a virtual link, which routers are configured?

** The configuration is between the ABRs, where one of the ABRs resides in Area 0 and the other

in the area that is disconnected from the backbone. Both of the ABRs are also members of the

transit area. Having created the virtual link, both ABRs are now members of Area 0, the

disconnected area, and the transit area.

19: What does the command area 1 default-cost 15 achieve?

** The command area 1 default-cost 15 will assign a cost of 15 to the default route that is to be

propagated into the stub area. This command is configured on the ABR attached to the stub area.

20: Explain what is placed in the parameters area-id and router-id for the command area

area-id virtual-link router-id.

** The parameter area-id is the area ID of the transit area. So if the ABR in Area 0 is creating a

virtual link with the ABR in Area 3 through Area 2, the area ID stated in the command is Area 2.

The router ID is the router ID of the router with whom the link is to be formed and a neighbor

relationship and adjacency established.

IP Routing Principles

1: In the routing table, a field indicates the source of the routing information. If the field

showed the letter C, what would this mean?

** A field showing the letter C would mean that the network is directly connected.

2: In the routing table, how is the next hop indicated?

** In the routing table, the next hop is indicated by the word via followed by an IP address. This is

the address of the next logical hop.

3: Cisco distinguishes between the routing and the switching functions. What is the



difference?

** The routing function is how the router learns the logical topology of the network. It decides

whether the datagram can be routed, which path to select if there is a choice, and to which

outgoing interface to queue the datagram. It operates at Layer 3 of the OSI stack.

The switching function is the forwarding of the frame from the inbound interface to an outbound

interface. It operates at Layer 2 of the OSI stack, not at Layer 3 like a router, because the routing or

Layer 3 function has already been completed.

4: Name the interior IP routing protocols that send the mask with the routing update.

** The interior IP routing protocols that send the mask with the routing update are EIGRP, OSPF,

IS-IS, and RIPv2.

5: Does VLSM require a classful or classless routing protocol, and why?

** VLSM requires a classless routing protocol because it needs the subnet mask to be sent with the

update.

6: State one of the characteristics of a classful routing protocol.

** The characteristics of a classful routing protocol are as follows:

- It summarizes at the network boundary.

- Routes exchanged between foreign networks are summarized to the NIC number.

- Within the same network (IANA classful network), subnet routes are exchanged by routers.

- All the interfaces on all the routers within a NIC number must share the same subnet mask.

- VLSM is not possible within the network



7: What is the command to show whether a specific network, such as 141.131.6.16, is

present in the routing table?

** The command to show whether a specific network, such as 141.131.6.16, is present in the

routing table is as follows:

show ip route 141.131.6.16

8: State one major difference between a classful protocol and a classless routing protocol.

** Major differences between classful and classless routing protocols include:

- The capability to use VLSM

- The capability to summarize at an administratively defined boundary, as opposed to summarizing

at the classful boundary

- The capability to maximize the logical address space

9: Describe briefly the difference between a routing and routed protocol.

** The routed protocol is the Layer 3 protocol used to transfer data from one end device to another

across the network. The routed protocol is the Layer 3 datagram that carries the application data in

addition to the upper-layer information.

The routing protocol is the protocol used to send updates between the routers about the networks

that exist in the organization, thereby allowing the routing process to determine the path of the

datagram across the network.

10: Describe the processes used to build and maintain the routing table.

** There are three steps involved in building and maintaining the routing table. These three



processes are independent and include:

The routing protocol, which actually sends the information about the routes or networks within the

autonomous system, such as RIPv1, IGRP, EIGRP

The routing table, which receives updates from the routing protocol and provides the forwarding

process with information on request

The forwarding process, which determines which path to select from the routing table in order to

forward a datagram

11: Give a brief explanation of the switching function.

** The switching function does the following:

- Checks the incoming frame for validity

- Checks whether the frame is addressed (at Layer 2) to the router

- Checks whether the frame is within the scope of the framing criteria (too big or too small)

- Checks whether the frame passes CRC

- Strips the Layer 2 header and trailer from the frame and checks the destination address against

the cache entries

- Creates the appropriate frame header and trailer (if there is an entry in cache for the destination

address) and forwards the frame to the outbound interface queue

12: What information is contained in the fast switching cache?

** If fast switching is enabled, the datagram is then examined again, and an entry is put into a route

cache. The entry in this cache consists of the following:



- An IP prefix

- The output interface

- The link-layer header to be used in forwarding the datagram

13: When would you use the command no auto-summary?

** Some routing protocols, such as BGP, RIPv2, and EIGRP, summarize at the network boundary

automatically. Summarization within the NIC number boundary must be configured manually, and

therefore autosummarization must first be disabled with the no auto-summary command.

14: When does OSPF send updates, and do they contain the entire routing table?

** Each OSPF router refreshes its LSA every 30 minutes. An LSA will be sent earlier if there is an

adjacency change.

15: Network convergence is when a network domain has learned about the new network

topology after a change has occurred in the domain. What is considered a network change

that would require network convergence?

** The accuracy of the table will be affected by how quickly it responds to changes in the network.

These changes include the following:

- Learning new networks

- Learning a better path to an existing network

- Learning that a network is no longer available

- Learning an alternative route to a network

16: When would you consider using a static route in your network?



** A static route would be configured for the following reasons:

- Links that have very low bandwidth, such as dialup links

- The administrator needs control over the link

- The link is a backup to the dynamically learned route

- There is only one path to the remote network, such as a stub network

- The router has very limited resources and cannot run a routing protocol

- The administrator needs to control the routing table to allow a classful protocol and a classless

routing protocol to populate the routing table

17: When would you consider using a default route in your network?

** Occasions for using a default route include:

- Connecting to the autonomous system from a stub network

- Connecting to the Internet

18: What command is used to configure ODR on a hub router?

** router odr is the only command needed to be configured on the hub router.

19: When would you consider using a floating static route in your network?

** Floating static routes are used when a backup route is required.

20: Describe some of the characteristics of classless routing protocols.



** Classless routing protocols include OSPF, EIGRP, RIPv2, IS-IS, and BGP.

- The characteristics of a classless routing protocol are:

- Router interfaces within the same network can have different subnet masks (VLSM).

- They support the use of classless interdomain routing (CIDR).

- Some routes can be summarized within the major NIC number. This is done manually.

Q-1, What kind of protocol routing keeps neighbors?

Answer-State Link

Q-2, what is the range of administrative distance?

Answer: 0-255

Q-3 describe the difference between unicast, multicast, dissemination and traffic?

Answer: Unicast traffic flows from a single source to a single destination MACaddress. Multicasttraffic flows from a single source MAC address many destinationsand uses a MAC address

functional. Broadcast traffic is one of singlesource all Ethernet devices in the segment. This isspecified by an address destinationMAC of all.

Q-4 What are the four different types of Ethernet encapsulation?

Answer: Since the encapsulation Cisco IPX command that ARPA, NOVELL-ether, SAP and SNAP

Q-5 What are the three main tasks of a transparent bridge?

Answer: Learning, Transmission, Filtering

Q-6 What kind of protocol routing is Enhanced Interior Gateway Routing Protocol?

Answer: Hybrid

Q-7 While troubleshooting a problem of network connectivity, the question ping command from thePC command, but the production shows "application times." In the OSI layer that this problem isassociated with?

Answer: The network layer



What Q-8 algorithm OSPF uses to calculate its route table?

Answer: OSPF uses the shortest route first (SPF) algorithm, which is also known as theDijkstraalgorithm.

Q-9 What is a heel area?

Answer: A heel of the zone is an area that does not accept updates from outside itsautonomousrouting system.

Q-10 What does the TTL field of an IP packet header?

Answer: The TTL field indicates the maximum time that a package can be in the router network.Each that the processes of this package decrements the TTL of 1. If Thevalue reacheszero, the packet is discarded in the network. The purpose ofthis field is to eliminate the possibility of an endless number of packets that traverse the network.

Q1. Which of the following is Class C IP address?

A. 10.10.14.118

B. 135.23.112.57

C. 191.200.199.199

D. 204.67.118.54

Correct Answer: D.

Explanation:IP addresses are written using decimal numbers separated by decimal points. This is called dotteddecimal notation of expressing IP addresses.

Q2. You have an IP of 156.233.42.56 with a subnet mask of 7 bits. How many hosts andsubnets are possible?

A. 126 hosts and 510 subnets

B. 128 subnets and 512 hosts

C. 510 hosts and 126 subnets

D. 512 subnets and 128 hosts

Correct answer: C

Explanation:

Class B network has the form N.N.H.H, the default subnet mask is 16 bits long.There is additional 7 bits to the default subnet mask. The total number of bits in subnet are 16+7 =23.This leaves us with 32-23 =9 bits for assigning to hosts.



7 bits of subnet mask corresponds to (2^7-2)=128-2 = 126 subnets.9 bits belonging to host addresses correspond to (2^9-2)=512-2 = 510 hosts.

Q3. Two sub layers of OSI Data Link layer are which of the following? [Select 2].

A. Logical Link Control

B. Data Link Control

C. Media Access Control

D. Physical Layer Control

Correct answer: A,C

Q4. Match the following:

A. Repeaters 1. Data Link Layer

B. Bridges 2. Network Layer

C. Routers 3. Physical Layer

Select the best combination:

A. A —>2, B—>3, C—>1

B. A—>3, B—->1, C—->2

C. A—>3,B—–>2, C—->1

D. A—->1, B—->2, C—->3

Correct answer: B

Q5. Which of the following are session layer standards? [Select 2].

A. NFS

B. SQL

C. JPG

D. MIDI

Correct answer: A,B

Q6. Match the corresponding layers of ISO and DoD models?

DoD Model <---------> ISO OSI Model



A. Process/Application 1. Application

B. Host-to-Host 2. Presentation

C. Internet 3. Session

D. Network Access 4. Transport

5. Network

6. Data Link

7. Physical

Choose best choice:

A. A->1+2; B->3+4; C->5; D->6+7

B. A->1+2+3; B->4; C->5; D->6+7

C. A->1+2+3; B->4; C->5+6; D->7

D. A->1+2+3; B->4+5; C->6; D->7

Correct answer: B

Q7. What is the command used to add a banner to a Cisco router configuration?

A. add banner

B. banner motd #

C. motd banner #

D. add banner #

Correct answer: B

Q8. What is the default administrative distance for RIP?

A. 100

B. 120

C. 0

D. 200Correct answer: B

Q9. The Cisco Catalyst 1900 switches support which three LAN switch types? [Select 3].



A. Store-and-Forward

B. FragmentFree

C. InstaSwitch

D. FastForward

Correct answer: A,B,D

Q10. Which is true regarding VLANs?

A. VLAN technology uses VLAN switches (layer 2) which is a substitute for routing technologywhich uses routers.

B. A VLAN has same collision domain

C. A VLAN has same broadcast domain

D. VLANs are less secure with respect to simple switch or Hub networks.

Correct answer: C

Q11. Your internet work consists entirely of Cisco devices. You have given a command“show cdp neighbors”. In the response, you get “S” under the head “Capability”. What doesthe letter “S” mean?

A. It means “Source Route Bridge”

B. It means “Host”

C. It means “Switch”

D. It means “Static”

Correct answer: C

Q12. You want to verify the encapsulation type being used at Data Link layer for interface s0.Which command can you use?

A. Sh ip protocol

B. sh int s0

C. sh ip interface

D. sh processes

Correct answer: B



Q13. You want to run 802.2 frame type on your Ethernet interface. Which encapsulation typehas to be chosen?

A. Ethernet_II

B. 802.2

C. SAP

D. SNAP

Answer is C

Q14. What does -1 signify in an extended IPX access list?

A. permit this host

B. deny this host

C. permit only this subnet

D. any host or any network

Correct answer: D

Q15. Which command sequence will allow only traffic from network 185.64.0.0 to enter interface s0?

A. access-list 25 permit 185.64.0.0 255.255.0.0int s0 ; ip access-list 25 out

B. access-list 25 permit 185.64.0.0 255.255.0.0int s0 ; ip access-group 25 out

C. access-list 25 permit 185.64.0.0 0.0.255.255int s0 ; ip access-list 25 in

D. access-list 25 permit 185.64.0.0 0.0.255.255int s0 ; ip access-group 25 in

Correct answer: D

Q16. Which of the following are reference points relevant to ISDN? [Select 2].

A. T

B. U

C. V

D. X



Correct answer: A,B

Q17. Which is true about VLAN Trunk Protocol? [Select 2].

A. VTP is statically configured and no built in intelligence is available.

B. VTP provides intelligence for configuring switches across the network.

C. VTP is not designed to distribute information across the switch fabric.

D. VTP is designed to distribute information across the switch fabric.

Correct answer: B, D

Q18. Which of the following is a term associated with WAN terminology / is a WAN device?[Select all that apply].

A. Demarc

B. DSU/CSU

C. Modem

D. CPE

Correct answer: A, B, C, D

Q19. Which of the following can be used to view the previous command you entered into aCisco router? [Select 2].

A. CTRL+F1

B. The Down Arrow

C. The Up Arrow

D. CTRL + P

Correct answer: C, D

Q20. What is true about static VLANs? [Choose the best answer].

A. The VLAN is configured by a TFTP server.

B. It automatically notify a new network user.

C. The administrator assigns VLAN by port.

D. Static VLAN are more appropriate when the switch fabric becomes more complex.

Correct answer: C



1 : IPX routing updates occur how often?

A.) Every 30 seconds

B.) Every 60 seconds

C.) Only as needed

D.) When the remote router asks for an update

Ans B

IPX RIP updates are exchanged every 60 seconds.

2 : Identify 3 methods not used to prevent routing loops?

A.) Holddown timers

B.) Sequence numbers

C.) Triggered updates

D.) Split horizon

E.) Area hierarchies

F.) Order of router startup

Ans B E F

Area hierarchies, sequence numbers and order of router startup all relate to Link State routing

protocols which do NOT incur routing loops.

3 : Identify the hardware component that stores the bootstrap program?

A.) ROM

B.) NVRAM

C.) Booter load

D.) RAM

E.) Flash

Ans A

ROM contains the boot strap code.

4 : Identify 3 characteristics of a connection oriented protocol?

A.) Path determination

B.) Flow control

C.) Acknowledgements

D.) Uses hop count as metric



E.) 3 step handshake

Ans B C E

Connection oriented protocols must first establish the connection (3 step handshake), employ

methods to acknowledge the receipt of data (acknowledgements) and slow down the flow of data if

required (flow control).

5 : What is the maximum hop count for IP RIP?

A.) Infinity

B.) 16

C.) 15

D.) 1

Ans C

15 is the maximum hop count, underscoring the size limitation of RIP

6 : Which of the following is a characteristic of a switch, but not of a repeater?

A.) Switches forward packets based on the IPX or IP address in the frame

B.) Switches forward packets based on the IP address in the frame

C.) Switches forward packets based on the MAC address in the frame

D.) Switches forward packets based only on the IP address in the packet

Ans C

A repeater regenerates the signal it receives, a switch makes decisions based upon MAC

addresses to determine whether a frame should be forwarded. Repeaters forward all packets.

7 : Ping uses which Internet layer protocol?

A.) RARP

B.) ICMP

C.) ARP

D.) FTP

Ans B

Internet Control Message Protocol - ICMP is a management protocol and messaging service

provider for IP. Its messages are carried as IP datagrams.ICMP is used in the following

events:Destination Unreachable - If a router cannot send an IP packet any further, it uses an ICMP

echo to send a message back to the sender notifying it that the remote node is unreachable.Buffer



Full - If a routers memory buffer is full ICMP will send out a message to the originator.Hops - Each

IP datagram is assigned a path. This consists of hops. If it goes through the maximum number of

hops, the packet is discarded and the discarding router sends an ICMP echo to the host. Ping -

Ping use ICMP echo message to check connectivity.

8 : Which is true regarding store-and-forward switching method?

A.) Latency varies depending on frame-length

B.) Latency is constant

C.) It is default for all Cisco switches

D.) It only reads the destination hardware address before forwarding the frame

Ans A

Store-and-Forward switching copies the entire frame into its buffer and computes the CRC. If a

CRC error is detected, the frame is discarded, or if the frame is a runt (less than 64 bytes including

the CRC) or a giant (more than 1518 bytes including the CRC). The LAN switch then looks up the

destination address in its switching table and determines the outgoing interface. The frame is then

forwarded to the outgoing interface. Cisco Catalyst 5000 switches uses the Store-and-Forward

method. The problem with Store-and-Forward switching is latency is increased. Latency also varies

with the size of the frame. The larger the frame, the more latency associated. This of course is due

to the fact that the entire frame is copied into its buffer before being forwarded.

9 : What does a metric of 16 hops represent when using RIP?

A.) Number of hops to the destination

B.) Destination unreachable

C.) Number of routers

D.) Bandwidth

Ans B

Routing Information Protocol (RIP) is a distance vector routing protocol that used hop count as its

metric. The maximum hop count is 15, 16 hops is considered unreachable. RIP updates are

broadcast every 30 seconds by default. RIP has an administrative distance of 120.

10 : You need to come up with a TCP/IP addressing scheme for your company. Which two

factors must you consider when you define the subnet mask for the network?

A.) The location of DHCP servers



B.) The volume of traffic on each subnet

C.) The number of subnets on the network

D.) The location of the default gateway

E.) The number of host IDs on each subnet

Ans C E

When determining which subnet mask to use, you must determine how many hosts and how many

subnets are required.

1 : LAN stands for which of the following?

A.) Local Area Network

B.) Local Arena Network

C.) Local Area News

D.) Logical Area Network

Ans A

LAN stands for Local Area Network

2: Which OSI layer performs code conversion, code formatting and encryption?

A.) Physical

B.) Data-Link

C.) Application

D.) Transport

E.) Presentation

F.) Network

Ans E

Layer 6 the Presentation layers performs this function.201 Identify the 3 methods routers learn

paths to destinations?

3 : Which two of the following protocols are used at the Transport layer?

A.) ARP

B.) UDP

C.) ICMP

D.) RARP

E.) TCP



F.) BootP

Ans B E

TCP and UDP operate at the Transport layer

4 : Which of the following provide correct information about a protocol at the transport layer

of the OSI model?

A.) UDP - Provides Connectionless datagrams service

B.) TCP - Provides Connection Oriented Services

C.) SMTP - Provides Mail Exchange

D.) IP - Route determination

E.) TCP - Provides Flow Control and Error Checking

F.) FTP - Transfers of Files

Ans A B E

Only TCP and UDP work at the Transport layer of the above choices. IP is a Network layer

protocol. SMTP and FTP are application layer protocols.

5 : Which protocol works at the Internet layer and is responsible for making routing

decisions?

A.) UDP

B.) IP

C.) TCP

D.) ARP

Ans B

Internet Protocol - IP provides routing and a single interface to the upper layers. No upper layer

protocol and now lower layer protocol have any functions relating to routing. IP receives segments

from the transport layer and fragments them into packets including the hosts IP address.

6 : Which layer is responsible for identifying and establishing the availability of the intended

communication partner?

A.) Application

B.) Presentation

C.) Transport

D.) Session

E.) Network



Ans : A

The Application layer performs the following: Synchronizing sending and receiving applications.

Program-to program communication. Identify and establish the availability of the intended

communication partner, and determine if sufficient resources exist for the communication. Popular

application protocols include WWW, SMTP, EDI, FTP, Telnet, and SNMP

7 : Based upon the 1st octet rule identify the range for a Class A address?

A.) 1 - 126

B.) 192 - 223

C.) 128 - 191

D.) 1 - 191

Ans A

Class A address has the 1st octet between 1 - 126. Class B between 128 - 191 and Class C

between 192 - 223.

8 : What does a Standard IP Access-list use as test criteria?

A.) IP source address

B.) IP source and destination address, protocol numbers and port numbers

C.) IPX source and destination address

D.) Source MAC address

Ans A

Standard IP access list use only source address.

9 : Identify the 3 methods routers learn paths to destinations?

A.) Dynamic routing

B.) None of the above, configured by default

C.) Default routes

D.) Administrative distance

E.) Static routes

Ans A C E

Routers can learn paths via 3 different sources; static routes, dynamic routing protocols (i.e. RIP)

and default routes.

10 : Identify the 3 Internet layer IP protocols?

A.) NetBios

B.) IPX

C.) ARP



D.) IP

E.) RARP

Ans C D E

NetBios and IPX are not layer 3 IP protocols. IP - Internet Protocol, ARP - Address Resolution

Protocol and RARP - Reverse Address Resolution Protocol.

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