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Cisco CCNP SWITCH 642-813 Exam Questions with Explanation–Chapter 1(1-5)

Chapter 1 – Implement VLAN based solution, given a network design and a set of requirements

QUESTION NO: 1
Which method of Layer 3 switching uses a forwarding information base (FIB)?
A. Topology-based switching
B. Demand-based switching
C. Route caching
D. Flow-based switching
E. None of the other alternatives apply
Answer: A
Explanation:
The Layer 3 engine (essentially a router) maintains routing information, whether from static routes or dynamic routing protocols. Basically, the routing table is reformatted into an ordered list with the most specific route first, for each IP destination subnet in the table. The new format is called a Forwarding Information Base (FIB) and contains routing or forwarding information that the network prefix can reference. In other words, a route to 10.1.0.0/16 might be contained in the FIB, along with routes to 10.1.1.0/24 and 10.1.1.128/25, if those exist. Notice that these examples are increasingly more specific subnets. In the FIB, these would be ordered with the most specific, or longest match, first, followed by less specific subnets. When the switch receives a packet, it can easily examine the destination address and find the longest match entry in the FIB. The FIB also contains the next-hop address for each entry. When a longest match entry is found in the FIB, the Layer 3 next-hop address is found, too.

QUESTION NO: 2
Which two statements are true about best practices in VLAN design? (Choose two.)
A. Routing should occur at the access layer if voice VLANs are utilized. Otherwise, routing should occur at the distribution layer.
B. Routing should always be performed at the distribution layer.
C. VLANs should be localized to a switch.
D. VLANs should be localized to a single switch unless voice VLANs are being utilized.
E. Routing should not be performed between VLANs located on separate switches.
Answer: B,C
Explanation:
In the distribution layer, uplinks from all access layer devices are aggregated, or come together. The distribution layer switches must be capable of processing the total volume of traffic from all the connected devices. These switches should have a port density of high-speed links to support the collection of access layer switches. VLANs and broadcast domains converge at the distribution layer, requiring routing, filtering, and security. The switches at this layer must be capable of performing multilayer switching with high throughput. Only certain Catalyst switch models can provide multilayer switching; be sure to understand which ones can do this.
A switched environment offers the technology to overcome flat network limitations. Switched networks can be subdivided into VLANs. By definition, a VLAN is a single broadcast domain. All devices connected to the VLAN receive broadcasts from other VLAN members. However, devices connected to a different VLAN will not receive those same broadcasts. (Naturally, VLAN members also receive unicast packets directed toward them from other VLAN members.)
A VLAN consists of defined members communicating as a logical network segment. In contrast, a physical segment consists of devices that must be connected to a physical cable segment. A VLAN can have connected members located anywhere in the campus network, as long as VLAN connectivity is provided between all members. Layer 2 switches are configured with a VLAN mapping and provide the logical connectivity between the VLAN members.

QUESTION NO: 3
Refer to the exhibit. On the basis of the information provided in the exhibit, which two sets of procedures are best practices for Layer 2 and 3 failover alignment? (Choose two.)
 
A. Configure the D-SW1 switch as the active HSRP router and the STP root for all VLANs. Configure the D-SW2 switch as the standby HSRP router and backup STP root for all VLANs.
B. Configure the D-SW1 switch as the standby HSRP router and the STP root for VLANs 11 and
110. Configure the D-SW2 switch as the standby HSRP router and the STP root for VLANs 12 and  120.
C. Configure the D-SW1 switch as the active HSRP router and the STP root for VLANs 11 and
110. Configure the D-SW2 switch as the active HSRP router and the STP root for VLANs 12 and  120.
D. Configure the D-SW2 switch as the active HSRP router and the STP root for all VLANs. Configure the D-SW1 switch as the standby HSRP router and backup STP root for all VLANs.
E. Configure the D-SW1 switch as the active HSRP router and the backup STP root for VLANs 11 and 110. Configure the D-SW2 switch as the active HSRP router and the backup STP root for VLANs 12 and 120.
F. Configure the D-SW1 switch as the standby HSRP router and the backup STP root for VLANs 12 and 120. Configure the D-SW2 switch as the standby HSRP router and the backup STP root for VLANs 11 and 110.
Answer: C,F
Explanation:
Basically, each of the routers that provides redundancy for a given gateway address is assigned to a common HSRP group. One router is elected as the primary, or active, HSRP router, another is elected as the standby HSRP router, and all the others remain in the listen HSRP state. The
routers exchange HSRP hello messages at regular intervals, so they can remain aware of each other’s existence, as well as that of the active router.
HSRP election is based on a priority value (0 to 255) that is configured on each router in the group. By default, the priority is 100. The router with the highest priority value (255 is highest) becomes the active router for the group. If all router priorities are equal or set to the default value, the router with the highest IP address on the HSRP interface becomes the active router. To set the priority, use the following interface configuration command: Switch(config-if)# standby group priority priority
When HSRP is configured on an interface, the router progresses through a series of states before becoming active. This forces a router to listen for others in a group and see where it fits into the pecking order. The HSRP state sequence is Disabled, Init, Listen, Speak, Standby, and, finally, Active. You can configure a router to preempt or immediately take over the active role if its priority is the highest at any time. Use the following interface configuration command to allow preemption: Switch(config-if)# standby group preempt [delay seconds]

QUESTION NO: 4
If you needed to transport traffic coming from multiple VLANs (connected between switches), and your CTO was insistent on using an open standard, which protocol would you use?
A. 802.11B
B. spanning-tree
C. 802.1Q
D. ISL
E. VTP
F. Q.921
Answer: C
Explanation:
The act involved in the above question is trunking. The two trunking protocols in the answer choices are: 802.1Q and ISL. ISL is Cisco proprietary and IEEE 802.1Q is based on an open standard. When non-Cisco switches are used along with Cisco switches and trunking is required, it is best to use the 802.1Q encapsulation.

QUESTION NO: 5
Under what circumstances should an administrator prefer local VLANs over end-to-end VLANs?
A. Eighty percent of traffic on the network is destined for Internet sites.
B. There are common sets of traffic filtering requirements for workgroups located in multiple buildings.
C. Eighty percent of a workgroup’s traffic is to the workgroup’s own local server.
D. Users are grouped into VLANs independent of physical location.
E. None of the other alternatives apply
Answer: A
Explanation:
This geographic location can be as large as an entire building or as small as a single switch inside a wiring closet. In a geographic VLAN structure, it is typical to find 80 percent of the traffic remote to the user (server farms and so on) and 20 percent of the traffic local to the user (local server, printers, and so on).
Reference: Building Cisco Multilayer Switched Networks (Cisco Press) page 93

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