CISCO CCNA Exam – Q163

Refer to the exhibit.
CISCO CCNA Exam – Q163

Which of these statements correctly describes the state of the switch once the boot process has been completed?

A. As FastEthernet0/12 will be the last to come up, it will be blocked by STP.
B. Remote access management of this switch will not be possible without configuration change.
C. More VLANs will need to be created for this switch.
D. The switch will need a different IOS code in order to support VLANs and STP.

Correct Answer: B

Explanation:
Notice the line, which says “Interface VLAN1, changed state to administratively down”. This shows that VLAN1 is shut down. Hence remote management of this switch is not possible unless VLAN1 is brought back up. Since VLAN1 is the only interface shown in the output, you have to assume that no other VLAN interface has been configured with an IP Address.

Incorrect Answers:
A. Whether a port is blocked or not by STP does not depend on the order in which the port became active.
C. Whether or not more VLANs are needed is not clear form the output.
D. 12.2(25)SEE2 LANBASE IOS code is capable of handling VLANs and STP. In general any 12.2 code can handle these features.

CISCO CCNA Exam – Q162

Two routers named Atlanta and Brevard are connected via their serial interfaces as illustrated, but they are unable to communicate. The Atlanta router is known to have the correct configuration.
CISCO CCNA Exam – Q162

Given the partial configurations, identify the fault on the Brevard router that is causing the lack of connectivity.

A. incompatible IP address
B. insufficient bandwidth
C. incorrect subnet mask
D. incompatible encapsulation
E. link reliability too low
F. IPCP closed

Correct Answer: D

Explanation:
Because Interface Serial 0 of Atlanta Router has 192.168.10.1 And Interface Serial 1 of Router Brevard has 192.168.11.2. These are from different network.

CISCO CCNA Exam – Q161

Users on the 172.17.22.0 network cannot reach the server located on the 172.31.5.0 network. The network administrator connected to router Coffee via the console port, issued the show ip route command, and was able to ping the server.
CISCO CCNA Exam – Q161

Based on the output of the show ip route command and the topology shown in the graphic, what is the cause of the failure?

A. The network has not fully converged.
B. IP routing is not enabled.
C. A static route is configured incorrectly.
D. The FastEthernet interface on Coffee is disabled.
E. The neighbor relationship table is not correctly updated.
F. The routing table on Coffee has not updated.

Correct Answer: C

Explanation:
The default route or the static route was configured with incorrect next-hop ip address 172.19.22.2. The correct IP address will be 172.18.22.2 to reach server located on 172.31.5.0 network. IP route 0.0.0.0 0.0.0.0 172.18.22.2

CISCO CCNA Exam – Q160

A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. Given the information in the partial configuration shown below, what configuration error is causing this problem?

Router(config)# router ospf 1
Router(config-router)# network 10.0.0.0 255.0.0.0 area 0

A. The process id is configured improperly.
B. The OSPF area is configured improperly.
C. The network wildcard mask is configured improperly.
D. The network number is configured improperly.
E. The AS is configured improperly.
F. The network subnet mask is configured improperly.

Correct Answer: C

Explanation:
When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”

CISCO CCNA Exam – Q159

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 Answers: A, D

Explanation:
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

We can see OSPF Router ID will be used as source of Type 1 LSA. Also the router will chose the highest loopback interface as its OSPF router ID (if available).

CISCO CCNA Exam – Q158

What are two benefits of using a single OSPF area network design? (Choose two.)

A. It is less CPU intensive for routers in the single area.
B. It reduces the types of LSAs that are generated.
C. It removes the need for virtual links.
D. It increases LSA response times.
E. It reduces the number of required OSPF neighbor adjacencies.

Correct Answers: B, C

Explanation:
OSPF uses a LSDB (link state database) and fills this with LSAs (link state advertisement). The link types are as follows:

  • LSA Type 1: Router LSA
  • LSA Type 2: Network LSA
  • LSA Type 3: Summary LSA
  • LSA Type 4: Summary ASBR LSA
  • LSA Type 5: Autonomous system external LSA
  • LSA Type 6: Multicast OSPF LSA
  • LSA Type 7: Not-so-stubby area LSA
  • LSA Type 8: External attribute LSA for BGP

If all routers are in the same area, then many of these LSA types (Summary ASBR LSA, external LSA, etc) will not be used and will not be generated by any router.
All areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, you can use a virtual link to connect to the backbone through a non-backbone area. You can also use virtual links to connect two parts of a partitioned backbone through a nonbackbone area. The area through which you configure the virtual link, known as a transit area, must have full routing information. The transit area cannot be a stub area. Virtual links are not ideal and should really only be used for temporary network solutions or migrations. However, if all locations are in a single OSPF area this is not needed.

CISCO CCNA Exam – Q157

When a router undergoes the exchange protocol within OSPF, in what order does it pass through each state?

A. exstart state > loading state > exchange state > full state
B. exstart state > exchange state > loading state > full state
C. exstart state > full state > loading state > exchange state
D. loading state > exchange state > full state > exstart state

Correct Answer: B

Explanation:
When OSPF adjacency is formed, a router goes through several state changes before it becomes fully adjacent with its neighbor. Those states are defined in the OSPF RFC 2328, section 10.1. The states are (in order) Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full.

Reference: http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13685-13.html

CISCO CCNA Exam – Q156

What are two enhancements that OSPFv3 supports over OSPFv2? (Choose two.)

A. It requires the use of ARP.
B. It can support multiple IPv6 subnets on a single link.
C. It supports up to 2 instances of OSPFv3 over a common link.
D. It routes over links rather than over networks.

Correct Answers: B, D

CISCO CCNA Exam – Q155

What are two enhancements that OSPFv3 supports over OSPFv2? (Choose two.)

A. It requires the use of ARP.
B. It can support multiple IPv6 subnets on a single link.
C. It supports up to 2 instances of OSPFv3 over a common link.
D. It routes over links rather than over networks.

Correct Answers: B, D

Explanation:
Here is a list of the differences between OSPFv2 and OSPFv3:

  • They use different address families (OSPFv2 is for IPv4-only, OSPFv3 can be used for IPv6-only or both protocols
  • OSPFv3 introduces new LSA types
  • OSPFv3 has different packet format
  • OSPFv3 uses different flooding scope bits (U/S2/S1)
  • OSPFv3 adjacencies are formed over link-local IPv6 communications
  • OSPFv3 runs per-link rather than per-subnet
  • OSPFv3 supports multiple instances on a single link, Interfaces can have multiple IPv6 addresses
  • OSPFv3 uses multicast addresses FF02::5 (all OSPF routers), FF02::6 (all OSPF DRs)
  • OSPFv3 Neighbor Authentication done with IPsec (AH)
  • OSPFv2 Router ID (RID) must be manually configured, still a 32-bit number

CISCO CCNA Exam – Q154

What command sequence will configure a router to run OSPF and add network 10.1.1.0 /24 to area 0?

A.
router ospf area 0
network 10.1.1.0 255.255.255.0 area 0
B.
router ospf
network 10.1.1.0 0.0.0.255
C.
router ospf 1
network 10.1.1.0 0.0.0.255 area 0
D.
router ospf area 0
network 10.1.1.0 0.0.0.255 area 0
E.
router ospf
network 10.1.1.0 255.255.255.0 area 0
F.
router ospf 1
network 10.1.1.0 0.0.0.255

Correct Answer: C

Explanation:
Enabling OSPF

SUMMARY STEPS
1. enable
2. configure terminal
3. router ospf process-id
4. network ip-address wildcard-mask area area-id
5. end

DETAILED STEPS
CISCO CCNA Exam – Q154