Juniper Networks Certified Internet Associate docx

Answer: A Explanation: The inet.0 routing table is used to store IPv4 routesA. send an error message toward the ingress router Answer: A Explanation: Popping the MPLS Label Our definitio

Exam : JN0-201

Titl e : Juniper Networks Certified Internet Associate

Ver : 09.21.2006

QUESTION 1

Which two statements are true concerning the JUNOS software? (Choose two.)

A Processes are tightly integrated with each other

B Processes are fully independent from each other

C Processes run in a protected memory environment

D Processes may fail and cause a failure of the entire system

Answer: B, C

Explanation:

From Juniper.com, Benefits of the JUNOS operating system: Each user process runs in

its own protected memory space This ensures that the failure of one subsystem will not

negatively impact the operation of other subsystems executing over the operating system

The router stores bootable copies of the JUNOS software in three possible locations: the

internal flash disk, the hard drive, or the removable media The primary boot location is

the internal flash disk The hard drive is the secondary boot location, while the removable

media is used for disaster-recovery purposes

QUESTION 3

Which path will a packet follow within a Juniper Networks router after it enters an

interface and before a forwarding table lookup is performed?

A PIC I/O Manager, Buffer Manager, I/O Manager, Internet Processor

B PIC I/O Manager, Buffer Manager, Internet Processor, I/O Manager

C PIC I/O Manager, I/O Manager, Buffer Manager, Internet Processor

D PIC I/O Manager, I/O Manager, Internet Processor, Buffer Manager

Answer: C

Explanation:

When a data packet arrives on an interface, the PIC I/O Manager performs

error-checking, then transmits the packet to the I/O Manager The I/O Manager removes

the layer 2 header and segments the packet into 64-byte J-cells It then sends those J-cells

to the Inbound Distributed Buffer Manager The Buffer Manager then sends a

notification cell to the Internet Processor, which performs a forwarding table lookup

B IP packet with the Router Alert option set

C ICMP traceroute packet with TTL set to 5

D ICMP echo request addressed to 172.16.1.1

Answer: B

Explanation:

The PFE can't process some data packets in its normal fashion These packets are referred

to as exception packets Examples of exception packets are: Routing protocol updates,

Packets addressed to the router, Packets requiring generation of ICMP error messages, or

Packets containing an IP Options field

Answer B is correct because an IP Option field is set in the packet A,C, and D are all

examples of packets that are be forwarded through the router as none of them are

destined for the router or require special attention

QUESTION 5

From within the [edit] portion of the configuration, which command restores the

number 2 rollback file?

A rollback 2

B run rollback 2

C request system rollback 2

D run request system rollback 2

Answer: A

Explanation:

The JUNOS software saves up to nine previous configuration files The most recent

config file is called juniper.conf.1.gz and is number 1 The naming convention continues

with each older file incrementing by 1 You restore a config file with the rollback

command and the number of the config file to restore Rollback is a configuration mode

command not an operation mode command, so within [edit] it is not necessary to precede

the command with the command "run"

QUESTION 6

A network administrator would like to verify the active alarms on the interface

so-0/0/0.0 Which command displays this information?

A show alarms

B show interfaces terse

C show alarms extensive

D show interfaces extensive

Answer: D

Explanation:

The "show interfaces extensive" command displays all possible information about every

interface including active alarms and any error conditions

QUESTION 7

Which ASIC is responsible for segmenting a packet into 64-byte J-Cells?

A PIC I/O ASIC

B I/O Manager ASIC

C Buffer Manager ASIC

D Internet Processor ASIC

The removable media is the first boot location examined If the router finds a copy of

the JUNOS software there, it loads the software on the router This presents a possible

hazard in your network since all existing files and file systems on the router are erased

during this process This type of boot process returns the router to a factory default-type

environment and should be used only for disaster recovery If no removable media is

present, the router loads the software from the internal flash disk This is considered the

normal boot operation and should occur at each router start

Each logical interface in the JUNOS software has the ability to support one or more

protocol families The inet protocol family supports IP version 4 (IPv4) packets

The "monitor traffic" command prints packet headers to your terminal screen for

information sent or receive by the routing engine It is very similar in operation to the

Unix tcpdump utility

QUESTION 11

Which command ensures that a configuration file on a backup Routing Engine is

identical to the file on the primary Routing Engine?

One of the options for the "commit" command is "synchronize" When you have a router

with two routing engines installed, this option tells the router to apply the candidate

configuration to both routing engines

QUESTION 12

If there is a BGP next hop with equal preference in inet.0 and inet.3, which version

of the route will BGP use?

A the route in inet.3

B the route in inet.0

C the route with the lower metric

D It will randomly choose between inet.0 and inet.3

Answer: A

Explanation:

The inet.0 routing table is used to store IPv4 routes All routing protocols place

information into this table by default The inet.3 routing table contains the egress IP

address of a MPLS lable switched path (LSP) Routes are inserted into inet.3 by the

RSVP protocol In the case of a preference tie between the routing tables, the JUNOS

software prefers the inet.3 table and the LSP

QUESTION 13

When a router receives a label of zero it will

A perform a label pop

B perform a label swap

C perform a label push

D send an error message toward the ingress router

Answer: A

Explanation:

Popping the MPLS Label

Our definition of each router's role along the path of an LSP assumes the default JUNOS

software behavior of penultimate hop popping (PHP) In this case, the penultimate transit

router in the LSP performs the label pop operation Another option exists for popping the

MPLS from the data packet- ultimate hop popping

Ultimate hop popping occurs when the egress router itself performs the pop operation

This requires the egress router to perform two operations on the data packet: the pop and

an IPv4 lookup to forward the packet This dual operation places a larger processing

burden on the egress router, which prompts the use of PHP

The technical difference between PHP and ultimate hop popping comes in the action of

the egress router Based on its current configuration, the egress router signals different

MPLS upstream to the penultimate router A lvalue of 3 means the upstream router

should perform PHP and forward native IPv4 packets A lvalue of 0, on the other hand,

tells the upstream router to perform a l-swap operation and to forward the data

with an MPLS header attached (We discuss the definitions of the MPLS label values in

the "ls" section of this chapter.) A Juniper Networks router performs ultimate hop

popping when the explicit-null command is applied

QUESTION 14

In normal operation, what is the job of the penultimate router?

A It pops the label and sends the remaining data packet to the egress router

B It pushes an additional label on a packet and sends it to the egress router

C It swaps an incoming label with a label of 3 and sends it to the egress router

D It examines the IP packet and forwards the packet based on the destination IP address

Answer: A

Explanation:

The penultimate router, which is second to last along the path of the LSP, often performs

a label pop operation to remove the MPLS information from the data packet After

consulting the MPLS switching table, the router forwards the resulting data, a native IPv4

packet, to the egress router

QUESTION 15

Where must you configure a static LSP?

A on the egress router only

B on the ingress router only

C on all routers along the LSP path

D on the ingress and egress routers

You want to ensure that an LSP from router A to router D always goes through

router C, which is two hops away The ERO is configured as

A C loose

B D loose

C C strict

D B strict

Answer: A

Explanation:

The explicit route object (ERO) allows the path message to traverse the network using

information that is independent of the IGP shortest path An ERO configured with a loose

hop specifies that the LSP must transit the specified node(s) in the order given The IGP

shortest path is used between the loose hop nodes

QUESTION 17

Which RSVP object assigns a label to the LSP?

A Label Object

B Label Assign Object

C Record Route Object

D Label Request Object

Answer: A

Explanation:

Label Request Object

The label request object is encoded in the Path messages sent to the egress router This

object allows each router to assign a label value to the requested LSP When the Path

message is received, the local router allocates a label and stores it with the Path soft state

for that LSP When the Resv message arrives from the downstream neighbor, the label is

advertised upstream in an RSVP label object

QUESTION 18

If all OSPF routers on a broadcast network have the same OSPF priority, what

parameter is used to determine the new BDR at the same time of a DR failure?

The router priority of all participating routers is examined first, with the highest priority

router becoming the BDR Any router reporting a priority value of 0 is ineligible to

become either the DR or BDR In the event of a priority tie, the router ID of each router

is examined The highest value results in that router becoming the BDR

QUESTION 19

What is the purpouse of the OSPF link-state update packet?

A describes a change to the OSPF hello timer

B carries one or more link-state advertisements

C establishes and maintains neighbor relationships

D describes the contents of the entire link-state database

Answer: A

Explanation:

Information in the link-state database is populated through a Link State Advertisement

(LSA) Each LSA contains routing, metric, and topology information to describe a

portion of the OSPF network The local router advertises LSAs within a link-state update

packet to its neighboring routers

QUESTION 20

Why would you make a non-backbone area a stub or not-so-stubby area?

A to aggregate routes learned from the ABR

B to lower the cost of routes advertised by the ABR

C to connect a non-contiguous area to the backbone

D to decrease the size of the link-state database in that area

Answer: A

Explanation:

The OSPF stub area provides for a smaller link-state database by restricting the presence

of AS external LSAs (type 5) within the area A not-so-stubby area restricts type 5

external LSAs, but still allows for some external routes to be present in the database with

a new NSSA external LSA type 7

An Autonomous System boundary router (ASBR) connects networks running different

routing protocols (autonomous systems) An ASBR injects external routing knowledge

into an OSPF network

QUESTION 22

Which CLI command is used to see the current OSPF link-state database?

A show ospf database

B show ospf neighbor

C show protocols ospf

D show ospf link-state

During OSPF adjacency formation, in what state is a router when it is negotiating to

be in charge of the database synchronization process?

In the ExStart state, the local router and its neighbor establish which router is in charge of

the database synchronization process The higher router ID of the two neighbors controls

which router becomes the master

IDLE: After the BGP process starts, a TCP session is initiated with the remote peer The

local router transitions to the Connect state and begins listening for a connection initiated

by the remote peer

CONNECT: In this state, the local router is has seen a TCP connection attempt from a

peer and is waiting for the TCP session to be completed If it is successful, the local

router sends an Open message to the peer and transitions to the OPENSENT state

ACTIVE: In the active state, the local router is trying to establish a TCP session with its

peer If the session establishes successfully, an Open message is sent and the local router

transitions to the OPENSENT state

OPENSENT state is reached once TCP session is established Established designates a

fully operational OSPF connection

QUESTION 25

What are two ways that a valid IBGP peering session can be configured? (Choose

two.)

A via the accept x.x/y command

B via the TCP reachable physical interface addresses

C via remote loopbacks with the local-address command

D via UDP with the neighbor x.x.x.x command at the group level

Answer: B, C

Explanation:

Unlike EBGP peers, there is no requirement for physical connectivity between IBGP

peers TCP sessions are established based on the IP reachability between two peers This

session can be established between any configured IP interfaces on the two routers.\

QUESTION 26

When configuring an IBGP peering session between loopback interfaces, why is the

local-address option required?

When a router generates an IP packet, the source IP address becomes the address of the

outbound interface The local-address command changes the source IP address of the

BGP messages to the configured IP address Without this, a peer configured to use a

loopback address will never see a connection attempt from its configured neighbor It is

expecting connections from the loopback IP address The local router is attempting

connections from the egress interface IP address unless local-address is configured

QUESTION 27

What is the first step in the BGP route selection?

A The local router prefers the route with the shortest AS_PATH

B The router first verifies that it has a route to the BGP Next Hop IP address

C The local router prefers the route from the peer with the lowest peer ID address

D The local router prefers the route learned from an EBGP peer over a route learned

from an IBGP peer

Answer: A

Explanation:

The order of BGP route selection:

1 The next hop must be reachable

2 Highest local preference

3 Shortest AS Path

4 Smallest Origin attribute

5 Smallest Multiple Exit Discriminator (MED)

6 EGP routes preferred over IBGP routes

7 Smallest IGP metric to advertised BGP next-hop

8 Shortest cluster-list length if route reflection is used for IBGP

9 Smallest numerical ID

10 Smallest numerical IP address

QUESTION 28

Assume that a comparable configuration is applied to your peer in AS 11 and that

bi-directional TCP reachability has been achieved Which EBGP configuration will

allow the BGP session to become established?

The "autonomous system" command assigns the local AS number, so B and C aren't

correct since the peer is an EBGP peer in AS 11 The local AS must be 64 The "peer-as"

command defines the AS of the peer router Answer D has the peer-as set to 101 Answer

A has the correct configuration

The Open message is the first packet BGP sends to a peer after the TCP connection has

been established It allows the two peers to negotiate the parameters of the peer session

QUESTION 30

Which CLI command displays routes received from an EBGP peer?

A show bgp received routes x.x.x.x

B show bgp advertised routes x.x.x.x

C show route receive-protocol bgp x.x.x.x

D show route advertising-protocol bgp x.x.x.x

Answer: A

Explanation:

You can view routes advertised by a BGP peer on the local router by using the "show

route receive-protocol bgp neighbor-address" command

QUESTION 31

Which CLI command displays routes advertise to an EBG peer?

A show bgp received routes x.x.x.x

B show bgp advertised routes x.x.x.x

C show route receive-protocol bgp x.x.x.x

D show route advertising-protocol bgp x.x.x.x

Answer: A

Explanation:

You can view routes being advertised to a BGP peer on the local router by using the

command "show route advertising-protocol bgp neighbor-address" command

QUESTION 32

What are two purposes of the AS_PATH attribute? (Choose two.)

A route selection

B loop avoidance

C determining equal cost paths for reachability

D defining the application of other BGP attributes

Answer: A, B

BGP uses the AS path as a method to prevent routing loops It is also used as a

tie-breaker in the route selection process

QUESTION 33

The ORIGIN attribute describes the source of the BGP prefix Which three are

valid ORIGIN codes? (Choose three.)

The current BGP specification dictates three possible origin values:

IGP: The route was originally learned from an IGP on the source router IGP is

displayed with the character "I" and is encoded as a value of 0

EGP: The route was originally learned by the EGP protocol on the source router EGP is

displayed with the character "E" and is encoded as a value of 1

Incomplete: The route's source was unkown to the initial BGP router Incomplete is

displayed with the character "?" and is encoded as a value of 2

QUESTION 34

When is the default routing policy applied?

A only if no policies have been applied

B prior to evaluating any applied policy

C after all policies have been evaluated

D during the evaluation of every applied policy

Answer: A

Explanation:

All policy chains have an implicit default policy at the end This is the default action to

take if there is no match to any of the configured policies The default policy does not

have a "next policy" result It will always end the policy evaluation

QUESTION 35

How do you send static routes to a RIP neighbor?

A By default, RIP automatically sends static routes

B Configure the static route with a next hop of the RIP neighbor

C This is not possible, only RIP routes can be sent to a RIP neighbor

D Configure redistribute static under [edit protocols rip]

E Apply an export policy within RIP that matches on the routes, and accepts it

Answer: A

Explanation:

By default, the RIP protocol will have no knowledge of routes from other routing

protocols including static routes On a Juniper router, routing policies are used to

redistribute routes from one protocol to another To advertise any routes to a RIP

neighbor, an export policy must be created

The longer match type is similar to the orlonger match type The difference between

them is that longer will only match routes that are more specific than the specified route

It will exclude the specified route

Inbound route policies are applied by the "import" command Looking at the

configuration, the 3 policies gold-cust, silver-cust, and bronze-cust are applied to

inbound routes Answer A is the only answer that matches any of these policies

What happens to the route 10.0.56.0/24?

A The route is rejected

B The route is accepted

C The metric is set to 5 and the route is accepted

D The metric is set to 10 and the route is accepted

Answer: A

Explanation:

Specifying multiple match conditions in a policy imposes a logical AND on the

conditions on the candidate route It will match the policy only if it also matches all of

the specified conditions Within a policy term, multiple route filters can be paired with

other types of match conditions Multiple route-filters are evaluated with a logical OR

So for this configuration, 10.0.56.0/24 matches the route-filter "10.0.0.0/16 orlonger" As

long as the metric on the route is "5" it will be accepted Answer B is the most correct

QUESTION 39

What are three characteristics of RIPv2? (Choose three.)

A supports VLSM

B supports Kerberos authentication

C is backward compatible with RIPv1

D multicasts messages to RIP neighbors

E uses Hello Protocol for neighbor discovery

Answer: A, C, D

RIP version 2 adds some extensions to the RIP protocol Because it uses the same packet

types and formats as RIPv1, RIPv2 is backward compatible with RIPv1 By default, all

RIPv2 response updates include the subnet mask, which allows for support of VLSM

RIPv2 sends all request and response messages to a multicast address instead of a

broadcast address

RIPv2 does support authentication, but only using plain-text or MD5 passwords There is

also no Hello mechanism with RIP

QUESTION 40

What are three characteristics of RIP? (Choose three.)

A uses Bellman-Ford algorithm

B uses hop count as the metric

C supports maximum allowable hop count of 15

D floods updates to all RIP routers in the network

E sends updates only when a route metric changes

Answer: A, B, C

Explanation

D incorrect because it floods updates to all connected neighbors only Not all routers in

the network

E Triggered updates E is incorrect because updates are sent every 30 seconds regardless

of any route changes

QUESTION 41

Which two steps are required for RIP to redistribute IS-IS routes? (Choose two.)

A apply the redistribution policy to RIP as import

B apply the redistribution policy to RIP as export

C apply the redistribution policy to IS-IS as import

D apply the redistribution policy to IS-IS as export

E create a redistribution policy accepting the RIP routes

F create a redistribution policy accepting the IS-IS routes

Answer: B, F

By default, the RIP protocol will have no knowledge of routes from other routing

protocols including static routes On a Juniper router, routing policies are used to

redistribute routes from one protocol to another For RIP to learn the ISIS routes, a policy

must be configured to accept the ISIS routes For RIP to advertise the routes, a RIP

export policy must be configured accepting the new RIP routes

A RIP request packet is sent to a neighbor to request that the neighbor send all or part of

the neighbor's routing table

QUESTION 43

During all initial traffic flow, which routers do dense mode multicast protocols

assume want to receive multicast traffic?

A all routers in the network

B only routers with receivers attached

C only routers along the core based tree

D all routers along the shortest-path tree

Answer: A

Explanation:

Dense mode multicast routing protocols assume that every user segment in the network

wants to receive the data stream As the source begins transmitting data traffic destined

for the multicast group address, the routers in the network flood the traffic to each

segment in the network

As multicast traffic is received, a router checks the source IP address of the packets

against the RPF table If it finds that the receiving interface is in fact the best path back to

the source, it assumes that a routing loop doesn't exist and continues to forward the

traffic By default, JUNOS uses the inet.0 routing table to perform RPF checks

There are two different types of trees created by multicast networks: shared trees, and

source-based trees Both trees create a shortest-path tree from the receiver back to the

source

QUESTION 46

What type of IGMP message is sent by a host to describe the multicast traffic it

would like to receive?

There are two types of IGMP message of concern to hosts: Host Membership Query, and

Host Membership Report Multicast routers send Host Membership Query messages to

discover which host groups have members on their attached local networks Hosts

respond to a Query by generating Host Membership Reports reporting each host group to

which they belong on the network interface from which the Query was received

The JUNOS software provides the ability for a PIM interface to operate in both sparse

and dense modes simultaneously Sparse-dense mode is a requirement when you're using

Auto-RP as a rendezvous point election mechanism

The inet.0 routing table is the table used to store IPv4 unicast routes The inet.1 routing

table is used to store IPv4 multicast routes The inet.2 table is also used to store IPv4

unicast routes, however these routes are used by multicast routing protocols to prevent

routing loops The inet.3 routing table contains the egress IP address of a MPLS label

switched path (LSP)

QUESTION 49

Which statement is true about static routes?

A Static routes are never removed from the forwarding table

B By default, static routes are placed in the inet.1 routing table

C By default, a static route to a single destination prefix is assigned a preference value of

20

D Static routes are removed from the forwarding table when their nexthops are no longer

reachable

Answer: A

Explanation:

Static routes are assigned a preference of 5 The inet.0 routing table is used to store all

IPv4 unicast routes For a static route to be placed in the inet.0 routing table, the next hop

must be valid If a next-hop becomes unreachable, the route will be removed from the

routing table

QUESTION 50

Without using policy, the default for load balancing traffic to equal-cost destination

is to _

A randomly select one of the available next hops

B load balance per packet across all available next hops

C load balance per layer 3 microflow across all available next hops

D load balance per layer 4 microflow across all available next hops

Answer: A

Explanation:

The default installation of data in the forwarding table is one next hop per destination

Random selection places one of the equal cost routes in the routing table To change the

default configuration and enable load balancing, a policy must be configured

Directly connected routes have a preference value of 0 Static routes have a default

preference of 5 There are no routing protocols with default preferences of 1 or 17

QUESTION 52

How do you enable interface fe-0/0/0 under the [edit protocols isis] level to form

both a Level 1 and Level 2 adjacency?

A set interface fe-0/0/0.0

B set interface fe-0/0/0.0 all level

C set interface fe-0/0/0.0 level 3 enable

D set interface fe-0/0/0.0 level 1 level 2

Answer: A

Explanation:

The JUNOS software default configuration for ISIS is for the router to be configured as a

Level 1 and Level 2 (L1/L2) router To enable (L1/L2) adjacencies on the router, the isis

protocol just needs to be enabled on an interface

QUESTION 53

How often are IS-IS Hello packets transmitted?

A 3 seconds for DIS; 9 seconds for non-DIS

B 9 seconds for DIS; 3 seconds for non-DIS

C 10 seconds for DIS; 3 seconds for non-DIS

D 10 seconds for all routers

Answer: A

Explanation:

The default hold time for JUNOS software on LAN interfaces is 27 seconds unless the

router is the DIS The Hello time is (hold time / 3) so the default hello timer is 9 seconds

For DIS routers, the hold time is reduced to 9 seconds The hello timer is still (hold time /

3), so the default hello timer for a DIS router is 3 seconds

ISIS uses standard NSAP addressing as defined in ITU X.213 The first part of the

address indicates the ISIS area The field containing the system ID appears immediately

after the area field This can be thought of as the host portion of the address The last

portion of the NET address is the N-selector (SEL) byte

QUESTION 55

Two Level 2 routers are exchanging Hello packets with different Area IDs What

occurs between these routers?

A An Adjacency forms

B An Adjacency does not form

C An Adjacency forms but traffic is not forwarded

D No IS-IS PDUs are sent

Answer: A

Explanation:

The only requirement to form a Level 2 adjacency is that each end of the link reside

within Level 2 Level 1 adjacencies require that the area value of the two routers be

identical If the areas are different, only Level 2 adjacencies can form between the

routers

QUESTION 56

What command would you use to view an IS-IS adjacency?

A show iso neighbor

B show isis neighbor

C show iso adjacency

D show isis adjacency

Answer: A

Explanation:

You can verify ISIS adjacencies are working by using the "show isis adjacency"

command The other 3 commands are not valid show commands in JUNOS

QUESTION 57

Three IS-IS routers on a broadcast segment have different priority values

configured Which router is elected the DIS on that broadcast segment?

A the router with the lowest priority

B the route with the highest priority

C the router with the highest System ID

D the router with the highest IP address

Answer: A

Explanation:

Within ISIS, a pseudonode is elected to represent the broadcast link to the rest of the

network The pseudonode is called the DIS The router with the highest criteria is always

the DIS The first criteria checked is the DIS priority When two or more nodes share

priority values, the second criteria checked is the MAC address of the advertising router