[Free] Download New Updated (October 2016) Cisco 200-105 Real Exam 31-40

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QUESTION 31

Which two statements about the OSPF Router ID are true? (Choose two.)

 

A.

It identifies the source of a Type 1 LSA.

B.

It should be the same on all routers in an OSPF routing instance.

C.

By default, the lowest IP address on the router becomes the OSPF Router ID.

D.

The router automatically chooses the IP address of a loopback as the OSPF Router ID.

E.

It is created using the MAC Address of the loopback interface.

 

Correct Answer: AD

Explanation:

From the output of the “show ip ospf database”:

r120#show ip ospf data

OSPF Router with ID (10.0.0.120) (Process ID 1)

Next, who are the other routers in our area?

Router Link States (Area 1)

Link ID         ADV Router   Age   Seq#             Checksum Link count

10.0.0.111    10.0.0.111     600    0x8000023A  0x0092B3 1

10.0.0.112    10.0.0.112     1246  0x80000234   0x009CAC 1

10.0.0.113    10.0.0.113     148    0x8000022C  0x004399 3

10.0.0.120    10.0.0.120     152    0x80000240   0x0046CB 1

This tells us there are four routers in Area 1. The router with RID 10.0.0.113 has 3 links in Area 1, every one else has only 1 link. Also the router will chose the highest loopback interface as its OSPF router ID (if available).

 

 

QUESTION 32

Refer to Exhibit. The internetwork infrastructure of company XYZ consists of a single OSPF area as shown in the graphic. There is concern that a lack of router resources is impeding internetwork performance. As part of examining the router resources, the OSPF DRs need to be known. All the router OSPF priorities are at the default and the router IDs are shown with each router. Which routers are likely to have been elected as DR? (Choose two.)

 

clip_image002

 

A.

Corp-1

B.

Corp-2

C.

Corp-3

D.

Corp-4

E.

Branch-1

F.

Branch-2

 

Correct Answer: DF

Explanation:

There are 2 segments on the topology above which are separated by Corp-3 router. Each segment will have a DR so we have 2 DRs.

To select which router will become DR they will compare their router-IDs. The router with highest (best) router-ID will become DR. The router-ID is chosen in the order below:

The highest IP address assigned to a loopback (logical) interface.

If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.

In this question, the IP addresses of loopback interfaces are not mentioned so we will consider IP addresses of all active router’s physical interfaces. Router Corp-4 (10.1.40.40) & Branch-2 (10.2.20.20) have highest “active” IP addresses so they will become DRs.

 

 

QUESTION 33

What does a router do if it has no EIGRP feasible successor route to a destination network and the successor route to that destination network is in active status?

 

A.

It routes all traffic that is addressed to the destination network to the interface indicated in the routing table.

B.

It sends a copy of its neighbor table to all adjacent routers.

C.

It sends a multicast query packet to all adjacent neighbors requesting available routing paths to the destination network.

D.

It broadcasts Hello packets to all routers in the network to re-establish neighbor adjacencies.

 

Correct Answer: C

Explanation:

Introduction to EIGRP

 

Reference:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

 

Feasible Successors

A destination entry is moved from the topology table to the routing table when there is a feasible successor. All minimum cost paths to the destination form a set. From this set, the neighbors that have an advertised metric less than the current routing table metric are considered feasible successors.

 

Feasible successors are viewed by a router as neighbors that are downstream with respect to the destination.

 

These neighbors and the associated metrics are placed in the forwarding table.

 

When a neighbor changes the metric it has been advertising or a topology change occurs in the network, the set of feasible successors may have to be re-evaluated. However, this is not categorized as a route recomputation.

 

Route States

A topology table entry for a destination can have one of two states. A route is considered in the Passive state when a router is not performing a route recomputation. The route is in Active state when a router is undergoing a route recomputation. If there are always feasible successors, a route never has to go into Active state and avoids a route recomputation.

 

When there are no feasible successors, a route goes into Active state and a route recomputation occurs. A route recomputation commences with a router sending a query packet to all neighbors. Neighboring routers can either reply if they have feasible successors for the destination or optionally return a query indicating that they are performing a route recomputation. While in Active state, a router cannot change the next- hop neighbor it is using to forward packets. Once all replies are received for a given query, the destination can transition to Passive state and a new successor can be selected.

 

When a link to a neighbor that is the only feasible successor goes down, all routes through that neighbor commence a route recomputation and enter the Active state.

 

 

QUESTION 34

Which statement is true, as relates to classful or classless routing?

 

A.

Classful routing protocols send the subnet mask in routing updates.

B.

RIPv1 and OSPF are classless routing protocols.

C.

Automatic summarization at classful boundaries can cause problems on discontiguous subnets.

D.

EIGRP and OSPF are classful routing protocols and summarize routes by default.

 

Correct Answer: C

Explanation:

http://www.ciscopress.com/articles/article.asp?p=174107&seqNum=3

 

RIPv1, RIPv2, IGRP, and EIGRP all auto-summarize classful boundaries by default (OSPF does not).To make discontiguous networks work, meaning you don’t want classful boundries to summarize, you need to turn off auto-summary.

 

 

QUESTION 35

Refer to the exhibit. If the router Cisco returns the given output and has not had its router ID set manually, what value will OSPF use as its router ID?

 

clip_image004

 

A.

192.168.1.1

B.

172.16.1.1

C.

1.1.1.1

D.

2.2.2.2

 

Correct Answer: D

Explanation:

If a router-id is not configured manually in the OSPF routing process the router will automatically configure a router-id determined from the highest IP address of a logical interface (loopback interface) or the highest IP address of an active interface. If more than one loopback interfaces are configured, the router will compare the IP addresses of each of the interfaces and choose the highest IP address from the loopbacks.

 

 

 

 

QUESTION 36

Which parameter or parameters are used to calculate OSPF cost in Cisco routers?

 

A.

Bandwidth

B.

Bandwidth and Delay

C.

Bandwidth, Delay, and MTU

D.

Bandwidth, MTU, Reliability, Delay, and Load

 

Correct Answer: A

Explanation:

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml#t6

 

OSPF Cost

The cost (also called metric) of an interface in OSPF is an indication of the overhead required to send packets across a certain interface. The cost of an interface is inversely proportional to the bandwidth of that interface. A higher bandwidth indicates a lower cost. There is more overhead (higher cost) and time delays involved in crossing a 56k serial line than crossing a 10M Ethernet line. The formula used to calculate the cost is:

Cost= 10000 0000/bandwidth in bps

 

For example, it will cost 10 EXP8/10 EXP7 = 10 to cross a 10M Ethernet line and will cost 10 EXP8/1544000 =64 to cross a T1 line. By default, the cost of an interface is calculated based on the bandwidth; you can force the cost of an interface with the ip ospf cost <value> interface sub configuration mode command.

 

 

QUESTION 37

Which statement describes an EIGRP feasible successor route?

 

A.

A primary route, added to the routing table

B.

A backup route, added to the routing table

C.

A primary route, added to the topology table

D.

A backup route, added to the topology table

 

Correct Answer: D

Explanation:Two terms that appear often in the EIGRP world are “successor” and “feasible successor”. A successor is the route with the best metric to reach a destination. That route is stored in the routing table. A feasible successor is a backup path to reach that same destination that can be used immediately if the successor route fails. These backup routes are stored in the topology table.

Reference: http://study-ccna.com/eigrp-overview

 

 

 

 

 

 

 

 

 

 

 

 

 

 

QUESTION 38

DRAG DROP

clip_image006

 

Correct Answer:

clip_image008

 

 

QUESTION 39

Which statement describes the process ID that is used to run OSPF on a router?

 

A.

It is globally significant and is used to represent the AS number.

B.

It is locally significant and is used to identify an instance of the OSPF database.

C.

It is globally significant and is used to identify OSPF stub areas.

D.

It is locally significant and must be the same throughout an area.

 

Correct Answer: B

Explanation:

The Process ID for OSPF on a router is only locally significant and you can use the same number on each router, or each router can have a different number-it just doesn’t matter. The numbers you can use are from 1 to 65,535. Don’t get this confused with area numbers, which can be from 0 to 4.2 billion.

 

 

QUESTION 40

The internetwork infrastructure of company XYZ consists of a single OSPF area as shown in the graphic. There is concern that a lack of router resources is impeding internetwork performance. As part of examining the router resources, the OSPF DRs need to be known. All the router OSPF priorities are at the default and the router IDs are shown with each router. Which routers are likely to have been elected as DR? (Choose two.)

 

clip_image009

 

A.

Corp-1

B.

Corp-2

C.

Corp-3

D.

Corp-4

E.

Branch-1

F.

Branch-2

 

Correct Answer: DF

Explanation:

There are 2 segments on the topology above which are separated by Corp-3 router. Each segment will have a DR so we have 2 DRs. To select which router will become DR they will compare their router-IDs. The router with highest (best) router-ID will become DR. The router-ID is chosen in the order below:

The highest IP address assigned to a loopback (logical) interface. If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.

In this question, the IP addresses of loopback interfaces are not mentioned so we will consider IP addresses of all active router’s physical interfaces. Router Corp-4 (10.1.40.40) & Branch-2 (10.2.20.20) have highest “active” IP addresses so they will become DRs.

 

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