CCNA Routing and Switching v3.0

 

QUESTION 231

What levels will be trapped if the administrator executes the command

 

router(config)# logging trap 4 (Choose four)

 

A.

Emergency

B.

Notice

C.

Alert

D.

Error

E.

Warning

 

Correct Answer: ACDE

Explanation:

The Message Logging is divided into 8 levels as listed below:

 

Level Keyword Description

0 emergencies System is unusable

1 alerts Immediate action is needed

2 critical Critical conditions exist

3 errors Error conditions exist

4 warnings Warning conditions exist

5 notification Normal, but significant, conditions exist 6 informational Informational messages

7 debugging Debugging messages

 

If you specify a level with the “logging trap level” command, that level and all the higher levels will be logged. For example, by using the “logging trap 4 command, all the logging of emergencies, alerts, critical, errors, warnings will be logged.

 

 

QUESTION 232

A network engineer wants to allow a temporary entry for a remote user with a specific username and password so that the user can access the entire network over the Internet. Which ACL can be used?

 

A.

standard

B.

extended

C.

dynamic

D.

reflexive

 

Correct Answer: C

Explanation:

We can use a dynamic access list to authenticate a remote user with a specific username and password. The authentication process is done by the router or a central access server such as a TACACS+ or RADIUS server. The configuration of dynamic ACL can be read here:

http://www.cisco.com/en/US/tech/tk583/tk822/technologies_tech_note09186a0080094524.shtml

 

 

QUESTION 233

What are three features of the IPv6 protocol? (Choose three.)

 

A.

optional IPsec

B.

autoconfiguration

C.

no broadcasts

D.

complicated header

E.

plug-and-play

F.

checksums

 

Correct Answer: BCE

Explanation:

An important feature of IPv6 is that it allows plug and play option to the network devices by allowing them to configure themselves independently. It is possible to plug a node into an IPv6 network without requiring any human intervention. This fe
ature was critical to allow network connectivity to an increasing number of mobile devices. This is accomplished by autoconfiguration.

IPv6 does not implement traditional IP broadcast, i.e. the transmission of a packet to all hosts on the attached link using a special broadcast address, and therefore does not define broadcast addresses. In IPv6, the same result can be achieved by sending a packet to the link-local all nodes multicast group at address ff02::1, which is analogous to IPv4 multicast to address 224.0.0.1.

 

 

QUESTION 234

Which IPv6 address is valid?

 

A.

2001:0db8:0000:130F:0000:0000:08GC:140B

B.

2001:0db8:0:130H::87C:140B

C.

2031::130F::9C0:876A:130B

D.

2031:0:130F::9C0:876A:130B

 

Correct Answer: D

Explanation:

An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.

 

 

QUESTION 235

A national retail chain needs to design an IP addressing scheme to support a nationwide network. The company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate addressing scheme? (Choose two.)

 

A.

255.255.255.0

B.

255.255.255.128

C.

255.255.252.0

D.

255.255.255.224

E.

255.255.255.192

F.

255.255.248.0

 

Correct Answer: BE

Explanation:

Subnetting is used to break the network into smaller more efficient subnets to prevent excessive rates of Ethernet packet collision in a large network. Such subnets can be arranged hierarchically, with the organization’s network address space (see also Autonomous System) partitioned into a tree-like structure. Routers are used to manage traffic and constitute borders between subnets.

A routing prefix is the sequence of leading bits of an IP address that precede the portion of the address used as host identifier. In IPv4 networks, the routing prefix is often expressed as a “subnet mask”, which is a bit mask covering the number of bits used in the prefix. An IPv4 subnet mask is frequently expressed in quad-dotted decimal representation, e.g., 255.255.255.0 is the subnet mask for the 192.168.1.0 network with a 24-bit routing prefix (192.168.1.0/24).

 

 

QUESTION 236

Refer to the exhibit. What is the most efficient summarization that R1 can use to advertise its networks to R2?

 

clip_image002

 

A.

172.1.0.0/22

B.

172.1.0.0/21

C.

172.1.4.0/22

D.

172.1.4.0/24

172.1.5.0/24

172.1.6.0/24

172.1.7.0/24

E.

172.1.4.0/25

172.1.4.128/25

172.1.5.0/24

172.1.6.0/24

172.1.7.0/24

 

Correct Answer: C

Explanation:

The 172.1.4.0/22 subnet encompasses all routes from the IP range 172.1.4.0 – 172.1.7.255.

 

 

QUESTION 237

What authentication type is used by SNMPv2?

 

A.

HMAC-MD5

B.

HMAC-SHA

C.

CBC-DES

D.

community strings

 

Correct Answer: D

Explanation:

SNMP Versions

Cisco IOS software supports the following versions of SNMP:

 

clip_image004SNMPv1 — The Simple Network Management Protocol: A Full Internet Standard, defined in RFC 1157. (RFC 1157 replaces the earlier versions that were published as RFC 1067 and RFC 1098.) Security is based on community strings.

clip_image004[1]SNMPv2c — The community-string based Administrative Framework for SNMPv2. SNMPv2c (the “c” stands for “community”) is an Experimental Internet Protocol defined in RFC 1901, RFC 1905, and RFC 1906. SNMPv2c is an update of the protocol operations and data types of SNMPv2p (SNMPv2 Classic), and uses the community-based security model of SNMPv1.

clip_image004[2]SNMPv3 — Version 3 of SNMP. SNMPv3 is an interoperable standards-based protocol defined in RFCs 2273 to 2275. SNMPv3 provides secure access to devices by a combination of authenticating and encrypting packets over the network.

 

SNMP Security Models and Levels

Model

Level

Authentication

Encryption

What Happens

v1

noAuthNoPriv

Community String

No

Uses a community string match for authentication.

v2c

noAuthNoPriv

Community String

No

Uses a community string match for authentication.

v3

noAuthNoPriv

Username

No

Uses a username match for authentication.

v3

authNoPriv

MD5 or SHA

No

Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms.

v3

authPriv

MD5 or SHA

DES

Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms. Provides DES 56-bit encryption in addition to authentication based on the CBC-DES (DES-56) standard.

 

Refer
ence: http://www.cisco.com/c/en/us/td/docs/ios/12_2/configfun/configuration/guide/ffun_c/fcf014.html

 

 

QUESTION 238

Which two statements about static NAT translations are true? (Choose two.)

 

A.

They allow connections to be initiated from the outside.

B.

They require no inside or outside interface markings because addresses are statically defined.

C.

They are always present in the NAT table.

D.

They can be configured with access lists, to allow two or more connections to be initiated from the outside.

 

Correct Answer: AC

Explanation:

Static NAT is to map a single outside IP address to a single inside IP address. This is typically done to allow incoming connections from the outside (Internet) to the inside. Since these are static, they are always present in the NAT table even if they are not actively in use.

 

 

QUESTION 239

Refer to the exhibit. Which address range efficiently summarizes the routing table of the addresses for router Main?

 

clip_image005

 

A.

172.16.0.0./21

B.

172.16.0.0./20

C.

172.16.0.0./16

D.

172.16.0.0/18

 

Correct Answer: B

Explanation:

The 172.16.0.0./20 network is the best option as it includes all networks from 172.16.0.0 – 172.16.16.0 and does it more efficiently than the /16 and /18 subnets. The /21 subnet will not include all the other subnets in this one single summarized address.

 

 

QUESTION 240

Which two benefits are provided by using a hierarchical addressing network addressing scheme? (Choose two.)

 

A.

reduces routing table entries

B.

auto-negotiation of media rates

C.

efficient utilization of MAC addresses

D.

< font style="font-size: 10pt" color="#000000">dedicated communications between devices

E.

ease of management and troubleshooting

 

Correct Answer: AE

Explanation:

Here are some of the benefits of hierarchical addressing:

 

clip_image004[3]Reduced number of routing table entries — whether it is with your Internet routers or your internal routers, you should try to keep your routing tables as small as possible by using route summarization. Route summarization is a way of having a single IP address represent a collection of IP addresses; this is most easily accomplished when you employ a hierarchical addressing plan. By summarizing routes, you can keep your routing table entries (on the routers that receive the summarized routes) manageable, which offers the following benefits:

clip_image004[4]Efficient allocation of addresses–Hierarchical addressing lets you take advantage of all possible addresses because you group them contiguously.

Reference: http://www.ciscopress.com/articles/article.asp?p=174107

 

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