Practice Free JN0-281 Exam Online Questions
Question #11
Referring to the exhibit, which two statements are correct about the IP fabric? (Choose two.)
- A . Only traffic between pods must traverse the super spine devices.
- B . All traffic must traverse the super spine devices.
- C . This is a three-stage IP fabric.
- D . This is a five-stage fabric.
Correct Answer: AD
Question #12
When configuring High Availability components, which of the following practices are recommended? (Choose two)
- A . Regularly update firmware to non-recommended versions.
- B . Ensure physical redundancy of critical components.
- C . Use a single path for data and control traffic.
- D . Implement regular testing of failover mechanisms.
Correct Answer: BD
Question #13
Leaf and spine data centers are used to better accommodate which type of traffic?
- A . north-east
- B . east-west
- C . north-west
- D . south-east
Correct Answer: B
B
Explanation:
In modern data centers, the shift toward leaf-spine architectures is driven by the need to handle increased east-west traffic, which is traffic between servers within the same data center. Unlike traditional hierarchical data center designs, where most traffic was "north-south" (between users and servers), modern applications often involve server-to-server communication (east-west) to enable services like distributed databases, microservices, and virtualized workloads. Leaf-Spine Architecture:
Leaf Layer: This layer consists of switches that connect directly to servers or end-host devices. These switches serve as the access layer.
Spine Layer: The spine layer comprises high-performance switches that provide interconnectivity between leaf switches. Each leaf switch connects to every spine switch, creating a non-blocking fabric that optimizes traffic flow within the data center.
East-West Traffic Accommodation:
In traditional three-tier architectures (core, aggregation, access), traffic had to traverse multiple layers, leading to bottlenecks when servers communicated with each other. Leaf-spine architectures address this by creating multiple equal-cost paths between leaf switches and the spine. Since each leaf switch connects directly to every spine switch, the architecture facilitates quick, low-latency communication between servers, which is essential for east-west traffic flows. Juniper’s Role:
Juniper Networks provides a range of solutions that optimize for east-west traffic in a leaf-spine architecture, notably through:
QFX Series Switches: Juniper’s QFX series switches are designed for the leaf and spine architecture, delivering high throughput, low latency, and scalability to accommodate the traffic demands of modern data centers.
EVPN-VXLAN: Juniper uses EVPN-VXLAN to create a scalable Layer 2 and Layer 3 overlay network across the data center. This overlay helps enhance east-west traffic performance by enabling network segmentation and workload mobility across the entire fabric.
Key Features That Support East-West Traffic:
Equal-Cost Multipath (ECMP): ECMP enables the use of multiple paths between leaf and spine switches, balancing the traffic and preventing any one path from becoming a bottleneck. This is crucial in handling the high volume of east-west traffic.
Low Latency: Spine switches are typically high-performance devices that minimize the delay between leaf switches, which improves the efficiency of server-to-server communications.
Scalability: As the demand for east-west traffic grows, adding more leaf and spine switches is straightforward, maintaining consistent performance without redesigning the entire network. In summary, the leaf-spine architecture is primarily designed to handle the increase in east-west traffic within data centers, and Juniper provides robust solutions to enable this architecture through its switch platforms and software solutions like EVPN-VXLAN.
B
Explanation:
In modern data centers, the shift toward leaf-spine architectures is driven by the need to handle increased east-west traffic, which is traffic between servers within the same data center. Unlike traditional hierarchical data center designs, where most traffic was "north-south" (between users and servers), modern applications often involve server-to-server communication (east-west) to enable services like distributed databases, microservices, and virtualized workloads. Leaf-Spine Architecture:
Leaf Layer: This layer consists of switches that connect directly to servers or end-host devices. These switches serve as the access layer.
Spine Layer: The spine layer comprises high-performance switches that provide interconnectivity between leaf switches. Each leaf switch connects to every spine switch, creating a non-blocking fabric that optimizes traffic flow within the data center.
East-West Traffic Accommodation:
In traditional three-tier architectures (core, aggregation, access), traffic had to traverse multiple layers, leading to bottlenecks when servers communicated with each other. Leaf-spine architectures address this by creating multiple equal-cost paths between leaf switches and the spine. Since each leaf switch connects directly to every spine switch, the architecture facilitates quick, low-latency communication between servers, which is essential for east-west traffic flows. Juniper’s Role:
Juniper Networks provides a range of solutions that optimize for east-west traffic in a leaf-spine architecture, notably through:
QFX Series Switches: Juniper’s QFX series switches are designed for the leaf and spine architecture, delivering high throughput, low latency, and scalability to accommodate the traffic demands of modern data centers.
EVPN-VXLAN: Juniper uses EVPN-VXLAN to create a scalable Layer 2 and Layer 3 overlay network across the data center. This overlay helps enhance east-west traffic performance by enabling network segmentation and workload mobility across the entire fabric.
Key Features That Support East-West Traffic:
Equal-Cost Multipath (ECMP): ECMP enables the use of multiple paths between leaf and spine switches, balancing the traffic and preventing any one path from becoming a bottleneck. This is crucial in handling the high volume of east-west traffic.
Low Latency: Spine switches are typically high-performance devices that minimize the delay between leaf switches, which improves the efficiency of server-to-server communications.
Scalability: As the demand for east-west traffic grows, adding more leaf and spine switches is straightforward, maintaining consistent performance without redesigning the entire network. In summary, the leaf-spine architecture is primarily designed to handle the increase in east-west traffic within data centers, and Juniper provides robust solutions to enable this architecture through its switch platforms and software solutions like EVPN-VXLAN.
Question #14
How does a layer 2 switch populate its bridge table?
- A . It stores the protocol number of frames traversing the network.
- B . It stores both the source and destination MAC addresses of frames traversing the network.
- C . It stores the destination MAC address of frames traversing the network.
- D . It stores the source MAC address of frames traversing the network.
Correct Answer: D
Question #15
What type of BGP is used for routing within the same autonomous system?
- A . IBGP
- B . EBGP
- C . Static BGP
- D . Dynamic BGP
Correct Answer: A
Question #16
Referring to the exhibit, you notice that after committing the configuration, the ae0 and ae1 interfaces appear in a link down state.
Which statement is correct in this scenario?
- A . No operational interfaces have been added to the LAG interfaces.
- B . No traffic is traversing the LAG interfaces.
- C . The LAG interfaces are in a passive state.
- D . The LAG interfaces are in aggressive mode.
Correct Answer: A
A
Explanation:
In the exhibit, the ae0 and ae1 interfaces are in a link down state. This occurs when no physical interfaces (member interfaces) have been added to the LAG (Link Aggregation Group) interfaces, or the member interfaces are not operational.
Step-by-Step Breakdown:
LAG Configuration:
A LAG interface (aggregated Ethernet interface) is a logical interface that combines multiple physical interfaces for redundancy and increased bandwidth. The LAG will only be operational if at least one member interface is active and configured correctly.
No Operational Member Interfaces:
If no member interfaces are added or if the member interfaces are down, the LAG will remain in a down state, as shown in the exhibit for ae0 and ae1. Resolution:
Verify that physical interfaces have been added to the LAG using commands like:
LAG Interface Status: In Juniper, the link status of the LAG depends on its member interfaces, which must be operational for the LAG to function.
A
Explanation:
In the exhibit, the ae0 and ae1 interfaces are in a link down state. This occurs when no physical interfaces (member interfaces) have been added to the LAG (Link Aggregation Group) interfaces, or the member interfaces are not operational.
Step-by-Step Breakdown:
LAG Configuration:
A LAG interface (aggregated Ethernet interface) is a logical interface that combines multiple physical interfaces for redundancy and increased bandwidth. The LAG will only be operational if at least one member interface is active and configured correctly.
No Operational Member Interfaces:
If no member interfaces are added or if the member interfaces are down, the LAG will remain in a down state, as shown in the exhibit for ae0 and ae1. Resolution:
Verify that physical interfaces have been added to the LAG using commands like:
LAG Interface Status: In Juniper, the link status of the LAG depends on its member interfaces, which must be operational for the LAG to function.
Question #17
Which type of route is used to represent a summary of multiple smaller networks?
- A . Static route
- B . Aggregate route
- C . Generated route
- D . Dynamic route
Correct Answer: B
Question #18
What roles do the Designated Router (DR) and Backup Designated Router (BDR) play in OSPF?
- A . They redistribute routes between OSPF and non-OSPF networks.
- B . They are responsible for generating LSAs for external routes.
- C . They reduce the number of adjacencies on broadcast networks.
- D . They determine the shortest path first algorithm.
Correct Answer: C
Question #19
Which three technologies improve high availability and convergence in a data center network? (Choose three.)
- A . graceful restart (GR)
- B . Bidirectional Forwarding Detection (BFD)
- C . link loss adjacency
- D . Failover Group (FG)
- E . link aggregation group (LAG)
Correct Answer: A, B, E
A, B, E
Explanation:
High availability and fast convergence are critical in data center networks to minimize downtime and maintain optimal performance. The following technologies contribute to achieving these goals: Graceful Restart (GR):
GR allows routers to maintain forwarding state during control plane restarts, ensuring continuous packet forwarding while minimizing network disruptions. Bidirectional Forwarding Detection (BFD):
BFD provides fast detection of path failures, allowing routing protocols to converge quickly by detecting link failures much faster than traditional timers. Link Aggregation Group (LAG):
LAG increases both redundancy and bandwidth by combining multiple physical links into one logical
link, providing load balancing and fault tolerance.
Juniper
Reference: High Availability Techniques: These technologies are fundamental in ensuring rapid recovery and failover within Juniper-based data center environments.
A, B, E
Explanation:
High availability and fast convergence are critical in data center networks to minimize downtime and maintain optimal performance. The following technologies contribute to achieving these goals: Graceful Restart (GR):
GR allows routers to maintain forwarding state during control plane restarts, ensuring continuous packet forwarding while minimizing network disruptions. Bidirectional Forwarding Detection (BFD):
BFD provides fast detection of path failures, allowing routing protocols to converge quickly by detecting link failures much faster than traditional timers. Link Aggregation Group (LAG):
LAG increases both redundancy and bandwidth by combining multiple physical links into one logical
link, providing load balancing and fault tolerance.
Juniper
Reference: High Availability Techniques: These technologies are fundamental in ensuring rapid recovery and failover within Juniper-based data center environments.
Question #20
What information in the Ethernet header is used to populate the bridging table?
- A . destination address
- B . source address
- C . type
- D . protocol
Correct Answer: B
B
Explanation:
The source MAC address in the Ethernet header is used to populate the bridging table (also called the MAC address table) on a switch. When a frame arrives at a switch, the switch examines the source MAC address and records it along with the ingress port in its MAC address table.
Step-by-Step Breakdown:
Learning Process:
When an Ethernet frame arrives on a switch port, the switch looks at the source MAC address and adds this MAC address to the MAC table along with the port it was received on. This process is called MAC learning.
Purpose:
The switch uses this information to determine the correct port to send frames destined for that MAC address in future transmissions, thus ensuring efficient Layer 2 forwarding. Juniper
Reference: Ethernet Switching: Juniper switches use source MAC addresses to build and maintain the MAC address table, which is essential for Layer 2 switching.
B
Explanation:
The source MAC address in the Ethernet header is used to populate the bridging table (also called the MAC address table) on a switch. When a frame arrives at a switch, the switch examines the source MAC address and records it along with the ingress port in its MAC address table.
Step-by-Step Breakdown:
Learning Process:
When an Ethernet frame arrives on a switch port, the switch looks at the source MAC address and adds this MAC address to the MAC table along with the port it was received on. This process is called MAC learning.
Purpose:
The switch uses this information to determine the correct port to send frames destined for that MAC address in future transmissions, thus ensuring efficient Layer 2 forwarding. Juniper
Reference: Ethernet Switching: Juniper switches use source MAC addresses to build and maintain the MAC address table, which is essential for Layer 2 switching.