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In this article, I describe some CCNA 200-301 sample questions for practice before appearing in the CCNA 200-301 exam. The following questions are basic questions and related to the CCNA 200-301 sample questions set 49. There are multiple sample questions set on this website for prior practice online. All questions are described with relevant answers. You can take the following questions and answer as reference for CCNA 200-301 exam. You may also need to do more practice with other websites and books to practice the CCNA 200-301 sample questions set 49.
Question 1: What is STP?
STP stands for Spanning Tree Protocol, which is a network protocol used to prevent loops in Ethernet networks. Loops can cause broadcast storms and lead to network instability, slow performance, or complete network failure. STP works by dynamically creating a loop-free logical topology within a redundant physical network.
Here’s a brief explanation of STP with an example:
Example Scenario:
Consider a network with three switches (Switch A, Switch B, and Switch C) connected together in a triangular topology, forming a loop.
1. Initial Network Setup:
In the absence of STP, all links between the switches are active, allowing traffic to flow freely across all links. This scenario creates a loop in the network.
“`
Switch A
/ \
Switch B – Switch C
“`
2. Broadcast Storm Problem:
When a device sends a broadcast packet (e.g., ARP request or DHCP discovery) in this network, the packet will be forwarded by all switches to all connected segments. This behavior causes the broadcast packet to circulate endlessly through the loop, leading to a broadcast storm.
3. STP Operation:
To resolve the loop and prevent the broadcast storm, STP is enabled on all switches in the network. STP operates by designating one switch as the root bridge (usually the switch with the lowest bridge ID). The root bridge becomes the central reference point for the spanning tree.
In this example, let’s assume Switch A has the lowest bridge ID, so it becomes the root bridge.
4. Path Selection:
STP then determines the best path from the root bridge to each switch. It selects the shortest path with the least cost (calculated based on link speeds) as the active path, while other paths become blocked.
In this example, STP would block one of the links between Switch A and Switch B and one of the links between Switch A and Switch C, creating a loop-free logical topology.
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Switch A (Root Bridge)
| \
| \
Switch B – Switch C
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5. Traffic Flow:
Now, traffic can flow from Switch B to the root bridge (Switch A) via the active path (highlighted in green) and from Switch C to the root bridge (Switch A) via the other active path.
6. Link Failure Handling:
If any link in the active path fails, STP will automatically recompute the spanning tree and activate an alternative path to maintain connectivity while still avoiding loops.
In summary, STP is a protocol that ensures loop-free connectivity in Ethernet networks by dynamically calculating the shortest paths and blocking redundant links. By preventing loops, STP improves network stability and performance, ensuring that traffic flows efficiently without causing broadcast storms or other network issues. This is the answer to question 2 of CCNA 200-301 sample questions set 49.
Question 2: What is RSTP?
RSTP stands for Rapid Spanning Tree Protocol, which is an improvement over the original Spanning Tree Protocol (STP). RSTP is an IEEE 802.1w standard and provides faster convergence times in Ethernet networks, allowing for quicker adaptation to network topology changes. Like STP, RSTP’s primary purpose is to prevent network loops by creating a loop-free logical topology.
Here’s a brief explanation of RSTP with an example:
Example Scenario:
Consider a network with four switches (Switch A, Switch B, Switch C, and Switch D) connected together in a linear topology with a loop.
1. Initial Network Setup:
Without RSTP, all links between the switches are active, and the network forms a loop.
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Switch A – Switch B – Switch C – Switch D
“`
2. Broadcast Storm Problem:
Similar to STP, if a broadcast packet is sent in this network, it will circulate through the loop and create a broadcast storm, leading to network inefficiency and instability.
3. RSTP Operation:
RSTP enhances the convergence process compared to STP. It retains most of the concepts from STP but introduces faster mechanisms to transition the network to a stable state in the presence of topology changes.
4. Rapid Convergence:
RSTP achieves faster convergence through the following mechanisms:
a. Port States : RSTP introduces three port states: Discarding, Learning, and Forwarding. Port transitions between these states are faster than in STP.
b. Proposal and Agreement : RSTP uses a “proposal” and “agreement” mechanism to quickly determine which ports can transition to the Forwarding state, reducing convergence time.
c. Backup Ports : RSTP allows backup ports to transition to the Forwarding state rapidly if the active port fails.
5. Path Selection:
RSTP determines the best path from the root bridge to each switch using the same concept as STP. The shortest path with the least cost becomes the active path, while other paths become backup paths.
In this example, let’s assume Switch A is the root bridge.
6. Loop-Free Logical Topology:
RSTP would block one of the links in the loop, creating a loop-free logical topology.
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Switch A (Root Bridge) —- Switch B —– Switch C —– Switch D
| | |
Block Active Block
“`
7. Traffic Flow:
Traffic will flow from Switch D to the root bridge (Switch A) through the active path (highlighted in green), and the link between Switch B and Switch C will be blocked to avoid the loop.
8. Link Failure Handling:
If any link in the active path fails, RSTP will converge quickly and activate an alternative path to maintain connectivity while still avoiding loops.
In summary, RSTP is an enhanced version of STP that provides faster convergence times in Ethernet networks. It achieves this by introducing rapid port state transitions, proposal/agreement mechanisms, and quicker activation of backup paths. RSTP ensures a loop-free logical topology, preventing broadcast storms and improving network efficiency and stability. This is the answer to question 2 of CCNA 200-301 sample questions set 49.
Question 3: What is MSTP?
MSTP stands for Multiple Spanning Tree Protocol, which is an extension of the Rapid Spanning Tree Protocol (RSTP). MSTP is defined in IEEE 802.1s and provides a way to group multiple VLANs into a single spanning tree instance, reducing the overhead of running separate spanning tree instances for each VLAN. It allows for better scalability and resource utilization in large networks with many VLANs.
Here’s a brief explanation of MSTP with an example:
Example Scenario:
Consider a large enterprise network with multiple VLANs. Each VLAN has its own spanning tree instance under RSTP, leading to a large number of spanning trees that run independently.
1. Initial Network Setup:
Without MSTP, each VLAN has its own spanning tree instance, which can lead to inefficiency in terms of resource usage.
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VLAN 10 –> RSTP instance 1
VLAN 20 –> RSTP instance 2
VLAN 30 –> RSTP instance 3
.
.
.
“`
2. Resource Overhead:
Running a separate spanning tree instance for each VLAN consumes significant resources, including CPU processing power and memory on the switches.
3. MSTP Operation:
MSTP groups multiple VLANs into a logical entity called an MST Region. Within an MST Region, a single spanning tree is created, resulting in fewer spanning tree instances.
4. MST Regions and MSTIs:
Each MST Region is identified by a unique MST Region Identifier (MSTI). Within an MST Region, multiple VLANs can be mapped to one or more MSTIs, depending on the desired topology and requirements.
5. Convergence and Load Balancing:
MSTP provides rapid convergence, similar to RSTP, and allows for load balancing across multiple links using multiple spanning trees within the MST Region.
6. Mapping VLANs to MSTIs:
VLAN-to-MSTI mapping allows you to define which VLANs should be part of a particular MSTI. This mapping is done on each switch within the MST Region.
Example VLAN-to-MSTI Mapping:
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VLAN 10, 20 –> MSTI 1
VLAN 30, 40, 50 –> MSTI 2
VLAN 60, 70 –> MSTI 3
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7. Loop-Free Logical Topology:
MSTP ensures that only one spanning tree instance is active for each MST Region, preventing loops and broadcast storms.
In summary, MSTP is an extension of RSTP that reduces the number of spanning tree instances by grouping multiple VLANs into a single spanning tree within an MST Region. This optimization improves resource utilization and scalability in large networks with many VLANs. MSTP allows for rapid convergence, load balancing, and efficient loop prevention, providing a more streamlined and robust network topology. This is the answer to question 3 of CCNA 200-301 sample questions set 49.
Question 4: What is a VTP?
VTP stands for VLAN Trunking Protocol, and it is a Cisco proprietary protocol used to manage and distribute VLAN configuration information across a network of Cisco switches. VTP enables the efficient administration of VLANs by allowing changes made to one switch’s VLAN database to be automatically propagated to other switches in the same VTP domain.
Here’s a brief explanation of VTP with an example:
Example Scenario:
Consider a network with multiple Cisco switches in the same VTP domain. The network administrator wants to add a new VLAN to one of the switches and have it automatically updated on all other switches within the domain.
1. Initial VLAN Configuration:
All switches have the same initial VLAN configuration, which includes default VLANs such as VLAN 1 and possibly additional manually configured VLANs.
2. VTP Domain and Modes:
To enable VTP, all switches within the network must belong to the same VTP domain. Each switch can operate in one of three VTP modes: Server, Client, or Transparent.
– VTP Server: Switches in Server mode are responsible for creating, modifying, and deleting VLAN information. They advertise this information to other switches in the VTP domain.
– VTP Client: Switches in Client mode receive VLAN information from VTP Servers but cannot make changes to the VLAN database. They accept updates sent by VTP Servers.
– VTP Transparent: Switches in Transparent mode do not participate in VTP updates but can pass VTP advertisements through to other switches. They maintain their VLAN database separately and do not advertise their VLAN information.
3. Adding a New VLAN:
Suppose the network administrator wants to add a new VLAN (VLAN 20) to Switch A.
– The administrator configures Switch A in VTP Server mode and creates VLAN 20 on Switch A.
– Switch A will update its VLAN database with the new VLAN 20.
4. VTP Advertisement:
As a VTP Server, Switch A advertises the addition of VLAN 20 to all other switches in the same VTP domain.
5. VLAN Update on Other Switches:
Switches that are VTP Clients receive the advertisement from Switch A and update their VLAN databases to include VLAN 20 automatically.
6. Network-Wide VLAN Consistency:
With VTP, the VLAN database is synchronized across all switches in the VTP domain. Any changes made to the VLAN configuration on a VTP Server are propagated to all VTP Clients, ensuring network-wide VLAN consistency.
7. VTP Pruning:
VTP also supports a feature called VTP Pruning, which helps prevent unnecessary broadcast traffic by limiting broadcast and unknown unicast traffic for specific VLANs to only the switches that have active ports in those VLANs.
In summary, VTP is a Cisco proprietary protocol that simplifies VLAN administration in a network by allowing VLAN configuration changes on one switch (VTP Server) to be automatically distributed to other switches (VTP Clients) within the same VTP domain. This ensures consistency and efficiency in managing VLANs across a network of Cisco switches. This is the answer to question 4 of CCNA 200-301 sample questions set 49.
Question 5: What is PVST?
PVST stands for Per-VLAN Spanning Tree, and it is a Cisco proprietary implementation of the Spanning Tree Protocol (STP). PVST extends the standard STP by creating a separate spanning tree instance for each VLAN in a network. It allows each VLAN to have its own unique spanning tree, offering better load balancing and redundancy across different VLANs.
Here’s a brief explanation of PVST with an example:
Example Scenario:
Consider a network with multiple VLANs and Cisco switches. The network administrator wants to ensure that each VLAN has its own spanning tree instance, allowing for independent path selection and optimized network performance.
1. VLANs and STP:
In a traditional STP implementation (commonly known as CST – Common Spanning Tree), a single spanning tree is calculated for the entire network. This means that all VLANs share the same path, which may not be optimal for all traffic types.
2. PVST Operation:
With PVST, each VLAN has its own independent spanning tree instance. This allows for load balancing and redundancy specific to each VLAN.
3. Per-VLAN Spanning Tree Instances:
For example, if the network has three VLANs (VLAN 10, VLAN 20, and VLAN 30), PVST will create three separate spanning tree instances—one for each VLAN.
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VLAN 10 –> PVST instance 1
VLAN 20 –> PVST instance 2
VLAN 30 –> PVST instance 3
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4. Different Paths for Each VLAN:
With PVST, switches can choose different paths for each VLAN’s spanning tree instance. This means that traffic for each VLAN can take a path that is best suited for that VLAN’s requirements.
5. Link Utilization:
PVST can optimize link utilization by distributing traffic across different links based on the spanning tree instance associated with each VLAN.
6. Rapid Convergence:
PVST, being an extension of RSTP (Rapid Spanning Tree Protocol), offers rapid convergence in response to network topology changes, which is crucial for maintaining network stability.
7. Compatibility with STP:
PVST is backward compatible with traditional STP. If a non-Cisco switch is present in the network, PVST will automatically fall back to standard STP (CST) for that specific portion of the network.
In summary, PVST is a Cisco proprietary enhancement to the Spanning Tree Protocol (STP) that allows each VLAN to have its own independent spanning tree instance. By creating separate spanning trees for each VLAN, PVST provides better load balancing, redundancy, and optimized network performance in a multi-VLAN environment. This is the answer to question 5 of CCNA 200-301 sample questions set 49.
Conclusion for CCNA 200-301 sample questions set 49
In this article, I described 5 questions with answers related to CCNA 200-301 exam. I hope you found these questions helpful for the practice of the CCNA 200-301 exam. You may drop a comment below or contact us for any queries related to the above questions and answers for CCNA 200-301. Share the above questions If you found them useful. Happy reading!!
