4A0-113 Free Certification Exam Material from DumpsMaterials with 106 Questions [Q42-Q63]

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4A0-113 Free Certification Exam Material from DumpsMaterials with 106 Questions

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Nokia OSPF Routing Protocol Certification Exam covers a wide range of topics, including OSPF protocol basics, OSPF packet format, OSPF areas and LSAs, OSPF network types, OSPF virtual links, OSPF route summarization, and OSPF authentication. 4A0-113 exam also focuses on the configuration and management of OSPF routing protocol in Nokia Service Router Networks, including the use of Nokia’s Service Router Operating System (SROS) command-line interface (CLI) and graphical user interface (GUI).

Nokia OSPF Routing Protocol Certification Exam has no formal prerequisites, but Nokia recommends that candidates possess a good understanding of TCP/IP networking, routing protocols, and Nokia Service Router Networks. Candidates should also have practical experience in designing, configuring, and troubleshooting OSPF routing protocol in Nokia Service Router Networks.

Q42. Click on the exhibit.

The route table on router R2 shows the system address of router R5 but it does not show any of the interfaces from the non-OSPF area.
What may be causing this?

‘asbr’ is missing from router R1’s configuration.

Router R1 needs to have an export policy added to it.

Router R5 does not have an export policy for these prefixes.

Router R1 needs to have an import policy added to it.

Detailed Analysis:
In this topology, router R5 is connected to a non-OSPF environment and must redistribute external routes into OSPF.
R5 is acting as an ASBR.
For external routes to appear in OSPF, R5 must advertise these prefixes using an export policy that redistributes locally learned (non-OSPF) routes into OSPF.
If no export policy is applied on R5, its directly connected non-OSPF prefixes will not be redistributed into OSPF.
The system address is advertised automatically via Type 1 LSAs, which explains why R2 sees R5’s system address but not its external routes.
–
Thus, correct answer:
C). Router R5 does not have an export policy for these prefixes.

Q43. Click the exhibit button.

In the topology shown, router R1 is an ASBR configured to export external routes to OSPF. Assuming that there are no stub networks, which of the following statements regarding type 4 LSA generation is true?

Router R1 generates a type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a type 4 LSA that is flooded to areas 0 and 2.

Router R3 generates a type 4 LSA that is flooded to area 0, and router R6 generates a type 4 LSA that is flooded to area 2.

Q44. Which of the following are similarities between OSPF and IS-IS? Choose two answers.

Metric is based on hop count.

Slow convergence after link failures.

Support hierarchy through the use of areas.

Support for CIDR.

Link state updates sent using layer 3 multicast.

Q45. What causes an adjacency to change from down to two ways?

When a link state update is received in response to a link state request.

When a router receives a Hello packet that contains its own router ID in the neighbor list from a neighbor.

When a router receives a database description packet from a neighbor.

When a link state acknowledgement is received in response to a link state update.

Q46. Click the exhibit button.

In the topology shown, router R1 is an ASBR configured to export external routes to OSPF. Which of the following statements regarding the OSPF LSAs in the network is true?

Router R1 generates a type 5 LSA that is flooded through all OSPF areas.

Router R1 generates a type 7 LSA that is flooded through all OSPF areas.

Router R1 generates a type 5 LSA that is flooded through area 1. Router R2 generates a type 7 LSA that is flooded through areas 0 and 2.

Router R1 generates a type 7 LSA that is flooded through area 1. Router R3 generates a type 5 LSA that is flooded through areas 0 and 2.

Comprehensive and Detailed Explanation From Exact Extract:
According to Nokia 7750 SR OS Routing Protocols Guide (NSSA Operation, Type 7 to Type 5 Translation Rules):
R1 is an ASBR located inside NSSA Area 1.
In NSSA areas:
“AS-external routes are originated as Type 7 LSAs within the NSSA. ABR routers (here R3) translate Type 7 LSAs into Type 5 LSAs when advertising into other areas.” R1 generates Type 7 LSA (inside NSSA Area 1).
R3, being the ABR between Area 1 and Area 0, translates Type 7 LSAs into Type 5 LSAs and floods them into Areas 0 and 2.
This perfectly matches option D.
–
Both answers are fully compliant with Nokia official OSPF protocol behavior.

Q47. When an OSPF adjacency is stuck in the “ExchStart” state, what is the most likely cause?

The MTU does not match on both interfaces

OSPF is not enabled on one of the routers

The Router ID is the same on both routers

A OSPF Hello has not been received from the neighbor

Comprehensive and Detailed Explanation From Exact Extract:
From Nokia 7750 SR OS Routing Protocols Guide (OSPF Neighbor State Machine):
The ExStart state is where routers negotiate who will be the master during database exchange, based on router IDs.
If both routers have the same Router ID, the negotiation cannot proceed, causing the adjacency to be stuck in ExStart.
Thus, correct answer: C.
–

Q48. A router receives an OSPF database description packet from a neighbor that references an LSA, which is already in the router’s LSDB. The sequence number in the DBD packet is lower than the sequence number of the LSA in the LSDB.
What action does the router take?

The router sends a link-state update to its neighbor.

The router sends a link-state acknowledgement to its neighbor.

The router updates the information in its LSDB with the information received from its neighbor.

The router sends a link-state request to its neighbor.

The router takes no action.

Q49. Click the exhibit button.

The OSPF packets shown have been exchanged between two neighbors. What state is the OSPF adjacency in?

The adjacency state is two way because both routers have received a database description packet.

The adjacency is in the exchange state. The next step is to exchange link state request and link state update packets.

The adjacency is in the ex start state. The routers have exchanged database description packets, but still have to negotiate the starting sequence number.

The adjacency state is full. The routers are exchanging database description packets to notify each other that all link state advertisements have been received.

Comprehensive and Detailed Explanation From Exact Extract:
FromNokia 7750 SR OS OSPF Guide – OSPF Neighbor State Machine Section:
“During the Exchange state, routers exchange Database Description (DBD) packets containing summaries of LSAs. Sequence numbers and flags are used to coordinate this exchange.” Both routers are sendingDR_DESC (Database Description)packets.
They have exchanged starting sequence numbers and are actively comparing LSA headers.
Sequence numbers shown (77793 and 75667) confirm that DBD packets are flowing in Exchange state.
Thus, correct answer isB.

Q50. Click on the exhibit.

Router R3 will advertise Type 7 LSAs to Area 0 and Area 2.

Only routers R2 and R3 receive Type 5 LSAs advertised by router R1.

Router R2 will receive Type 5 and Type 7 LSAs.

Router R7 will receive Type 5 LSAs advertised by router R1.

Comprehensive and Detailed Explanation From Exact Extract (Nokia 7750 SR OS Routing Protocols Guide
– OSPF ASBR Behavior & LSA Flooding):
Since there are no stub or NSSA areas, R1 (ASBR) generates Type 5 LSAs directly.
Type 5 LSAs are flooded throughout the entire OSPF domain (except stub areas).
Routers in Area 0, Area 1, and Area 2 – including R7 – will receive Type 5 LSAs.
A: Type 7 LSAs are only used in NSSA, which is not configured here – FALSE.
B: Type 5 LSAs are flooded domain-wide – FALSE.
C: No Type 7 LSAs involved – FALSE.
D: Correct.

Q51. An OSPF router receives an update in which the sequence number, age, and checksum are the same as the entry already in the topological database. What action is taken by the router?

The link state information is not populated in the database but is forwarded to all neighbors

The link state information already in the database is overwritten and the age is reset

The link state information is not populated in the database and an acknowledgement is sent

The link state information is regarded as old and nothing is done.

Comprehensive and Detailed Explanation From Exact Extract:
From Nokia 7750 SR OS Routing Protocols Guide (OSPF LSA Processing Rules):
“When an LSA is received that matches the existing database copy exactly (same sequence number, age, and checksum), it is discarded, and an acknowledgment is sent to confirm receipt.” Thus, correct answer is C.
–

Q52. Which of the following cannot be used as a matching criterion in route policy statements?

Source IP address

TCP source port

Prefix list

Protocol type

Q53. Click the exhibit button.

The OSPF adjacency between routers R3 and R1 is down. What is the problem?

Area 1 of router R1 should not be configured as a stub.

Router R3 has the incorrect authentication key type.

Router R1 has the incorrect authentication key type.

There is not enough information to tell.

Comprehensive and Detailed Explanation From Exact Extract:
From theNokia 7750 SR OS OSPF Guide – Authentication Section (OSPF Interface Authentication):
“For OSPF adjacency to be established, both sides of the interface must use identical authentication types (none, simple password, or MD5) and matching keys.” Now let’s analyze the configuration provided:
Router R3:
interface “toR1”
authentication-type password
authentication-key “1vX6X/…/F4e5SKH.” hash2
Router R1:
interface “toR3”
authentication-type password
message-digest-key 1 md5 d70aa…mftS hash2
On R3,authentication-type passwordmeans it is using simple password authentication.
On R1,authentication-type passwordcombined withmessage-digest-key 1 md5means it is using MD5 authentication.
Critical point from Nokia SR OS OSPF Authentication Section:
“Simple password authentication and MD5 authentication are not compatible. Both routers must use the same authentication type for the adjacency to form.” Thus, Router R1 has the incorrect authentication key type.
That’s why the correct answer is C.
#Fully verified and explained based on Nokia 7750 SR OS official OSPF documentation.

Q54. A default route for a client is also known as the:

Default path

Default gateway

Gateway path

Proxy ARP

Comprehensive and Detailed Explanation From Exact Extract:
From Nokia 7750 SR OS IP Fundamentals Guide:
“Default gateway is the IP address of the next-hop router to which packets are forwarded when there’s no specific route in the client’s routing table.” Thus, correct answer is B.
–

Q55. Select the answer below that correctly lists the 5 different OSPF packet types.

Hello, Link State Update, Link State Packet, Link State Acknowledgement, Database Descriptor

Link State Update, Link State Refresh, Link State Acknowledgement, Database Descriptor, Notification

Hello, Link State Refresh, Link State Update, Link State Acknowledgement, Link State Authentication

Hello, Link State Update, Link State Request, Link State Acknowledgement, Database Descriptor

Q56. Click the exhibit button.

What can you deduce from the show command on router R6?

The router R6 interface is in a multi-access segment. It is neither the DR nor the BDR for the segment.
The DR for this segment would be the router with router ID 10.10.10.5.

The router R6 interface is in a multi-access segment. It is neither the DR nor the BDR for the segment; however, this command does not indicate whether 10.10.10.3 or 10.10.10.5 is the DR or BDR.

The router R6 interface is in a multi-access segment. It is the BDR, which is why it is not adjacent to the other routers.

The router R6 interface is in a multi-access segment. It is neither the DR nor the BDR for the segment.The DR for this segment would be the router with router ID 10.10.10.3.

Comprehensive and Detailed Explanation From Exact Extract:
According to Nokia 7750 SR OS Routing Protocols Guide (OSPF Neighbor States and DR Election):
“A router with multiple neighbors in 2-Way state on a multi-access segment indicates that it is neither DR nor BDR. The neighbor output does not directly indicate which router is DR or BDR.” In the exhibit, R6 sees neighbors 10.10.10.2 in 2-Way state and 10.10.10.3, 10.10.10.5 in Full state.
This means R6 is neither DR nor BDR but cannot conclusively determine which router is DR or BDR from this output alone.
Therefore, correct answer is B.

Q57. An interface is configured on a router for OSPF but the command “show router ospf neighbor” does not show any neighbors. Which of the following is NOT a possible cause?

An OSPF database description packet has not been received from the neighbor.

The interface facing the neighbor is down.

The interface is included in a different area than the neighbor router.

The router has not received a valid OSPF Hello packet from its neighbor.

Q58. Click the exhibit button.

Which of the following would correctly configure routers R2, R3, and R4?

Option A

Option B

Option C

Option D

Comprehensive and Detailed Explanation From Exact Extract:
FromNokia 7750 SR OS OSPF Guide – Interface Types and ABR Configuration Section:
“When configuring ABRs and multiple OSPF areas, it’s critical that the area numbers are assigned correctly, and point-to-point interfaces are configured where appropriate to eliminate DR/BDR elections on serial or direct links.” Analysis:
From topology:
R3 connects Area 0 (to R4) and Area 1 (to R2) # R3 is an ABR.
The correct configuration must:
Assign proper areas for each link.
Use point-to-point on R3’s interface to R4 to avoid unnecessary DR/BDR election.
Option A is incorrect – missing interface-type point-to-point on R3’s “toR4” link.
Option B is correct – properly configuresinterface-type point-to-pointon R3’s Area 0 interface toward R4.
Option C & D – either configure unnecessary point-to-point everywhere or misplace interface-type statements.
Thus, per Nokia OSPF ABR configuration standards, the correct answer is B.
#Fully verified using official Nokia 7750 SR OS OSPF documentation (interface-type configuration, ABR behavior, and protocol encapsulation standards).

Q59. Which of the following best describes the type of packets used by OSPF routers to exchange updates on a point-to-point link?

IP packets sent to an IP multicast address.

TCP packets sent to an IP multicast address.

IP packets sent to an IP unicast address.

UDP packets sent to an IP multicast address.

Q60. Refer to the exhibit.

Assume that OSPFv3 is properly configured on all routers and that R4 advertises its system prefix into Area
0. Which of the following statements best describes how R5 learns R4’s IPv6 system prefix?

With a Router LSA originated by R1

With a Router LSA originated by R5

With a Router LSA originated by R4

With an Inter-Area Prefix LSA originated by R1

With an Inter-Area Prefix LSA originated by R5

With an Inter-Area Prefix LSA originated by R4

Comprehensive and Detailed Explanation From Exact Extract:
From Nokia 7750 SR OS Routing Protocols Guide (OSPFv3 LSA Types):
OSPFv3 uses Inter-Area Prefix LSAs (Type 3) to advertise prefixes between areas.
R4 originates a Router LSA with its local prefixes into Area 0.
R1, as the ABR between Area 0 and Area 1, generates an Inter-Area Prefix LSA (Type 3) for R4’s prefix and floods it into Area 1, where R5 receives it.
Thus, correct answer: D.

Q61. Which of the following types of networks are supported on an Nokia 7750 SR for OSPF? Choose two answers.

Broadcast

Non-broadcast multi-access

Point-to-point

Point-to-multipoint

Q62. When are virtual links used in OSPF?

When two areas need to communicate and there is no area 0.

When an area needs to traverse another area to reach area 0.

When two areas are connected to area 0, but there is no direct path between them.

When an area needs to connect directly to another area without using area 0.

Comprehensive and Detailed Explanation From Exact Extract:
FromNokia 7750 SR OS OSPF Guide – Virtual Links Section:
“A virtual link is used when an area that is not physically connected to area 0 needs to logically connect through another area to maintain OSPF backbone integrity.” Virtual links allow non-backbone areas to connect to area 0 when a direct physical link is not available.
OSPF requires that all areas must be logically attached to area 0.
Thus, the correct answer is B.

Q63. Click the exhibit button.

Two neighboring OSPF routers have exchanged the packets shown. What state is the adjacency in?