What is the role of the Access/Edge Layer in a three-tiered network hierarchy?
The Access/Edge Layer connects endpoint devices, such as computers and printers, using regular switches, providing direct network access to users.
What is the role of the Core Layer in a three-tiered network hierarchy?
The Core Layer houses high-performance routers and switches, merging geographically separated networks and ensuring fast, reliable data transfer across the network backbone.
What is the role of the Distribution/Aggregation Layer in a three-tiered network hierarchy?
The Distribution/Aggregation Layer defines boundaries using access lists and filters, managing traffic flow between the Core and Access Layers while enforcing security policies.
What are the benefits of having three layers in a network hierarchy?
Performance by optimizing traffic flow. Management through clear role separation. Scalability by allowing easier network expansion. Redundancy for increased reliability and fault tolerance.
What is a Collapsed Core Network Architecture?
A Collapsed Core Network Architecture merges the Core and Distribution Layers into a single layer, creating a simplified architecture ideal for medium to small datacenters.
What is the role of the Leaf Layer in Spine and Leaf Architecture?
The Leaf Layer consists of access switches that aggregate traffic from servers and connect directly to the Spine Layer.
What is the role of the Spine Layer in Spine and Leaf Architecture?
The Spine Layer contains switches that interconnect all Leaf switches in a full-mesh topology, ensuring high bandwidth and low latency.
What is the Maximum Transmission Unit (MTU) for Ethernet?
1500 bytes—this is the largest payload size allowed in a standard Ethernet frame.
What does the Ethernet header include?
Destination MAC Address – who the frame is going to
Source MAC Address – who sent it
EtherType field – tells whether the payload is IPv4, IPv6, or something else.
What’s included in a Layer 2 frame besides the header?
A payload (the actual data being carried).
What are Jumbo Frames?
Frames that exceed the 1500-byte MTU—used in high-performance networks to reduce overhead.
What port role blocks traffic to prevent loops?
Non-designated port
You’re analyzing a segment between two non-root switches. One has a lower cost to the root. What port role does it get?
Designated port
What is a root port in STP?
The root port is the port on a non-root bridge that provides the best path to the root bridge. Each non-root switch has exactly one root port It’s used to forward traffic toward the root bridge
What is Spanning Tree Protocol (STP), what IEEE standard defines it, and what problem does it solve?
STP is defined by IEEE 802.1d. Prevents broadcast storms and network loops. Enables redundant links between switches while maintaining a loop-free topology.
What is the root bridge in STP, how is it elected, and what identifier is used in the election?
The root bridge is the central reference point in the STP topology. Elected based on the lowest Bridge ID (BID), which equals Priority value + MAC address. Lower BID wins; ties resolved by lowest MAC.
How is path cost calculated in STP, and what factors influence which port becomes the root port?
Faster cables = lower cost; slower cables = higher cost. If costs are equal, the lowest port number is chosen.
A network engineer is tasked with extending a layer 2 network across multiple data centers using a layer 3 infrastructure. They implement a virtualization technology that encapsulates Ethernet frames within UDP packets to create scalable, agile virtual networks. What technology is being used?
Virtual Extensible Local Area Network (VXLAN), which enables layer 2 extension over layer 3 using network overlays and UDP encapsulation.
What is the primary Layer 2 protocol used in modern networks, and why is it preferred?
Ethernet — preferred for its simplicity, scalability, and efficiency. Uses contention-based access for bandwidth optimization.
Compare deterministic vs. contention-based access methods.
Deterministic Access: Organized and predictable; devices take turns in a set order.
Contention-based Access: Devices compete for access; more chaotic but efficient use of bandwidth.
For CSMA/CD, list what each part stands for and explain how it manages collisions.
Carrier Sense (CS): Devices listen for existing transmissions before sending
Multiple Access (MA): Many devices share the same medium
Collision Detection (CD): Devices detect collisions and stop transmitting CSMA/CD helps manage access and recover from collisions in Ethernet networks.
Why is CSMA/CD less relevant in modern Ethernet networks?
Modern Ethernet uses full-duplex switching, eliminating collisions. CSMA/CD was essential in legacy half-duplex environments
What is the purpose of a random back-off timer in Ethernet networks, and when is it used?
Used after a collision is detected (in CSMA/CD environments). Devices pause transmission and select a random back-off time before retrying—reduces repeated collisions.
Define what a VLAN is, including its OSI layer, function, and how switches handle VLAN tagging.
Segments traffic into separate broadcast domains. Operates at Layer 2 (Data Link layer). Switches tag each data frame with a VLAN ID to define its VLAN membership.
-
Network Fundamentals43
-
Routing15
-
OSI Model53
-
Documentation and Processes8
-
Ethernet Switching45
-
Orchestration and Automation9
-
IP Addressing44
-
WAN Connections12
-
Wireless Network30
-
Ports and Protocols35
-
Media and Connectors40
-
Distribution Systems (HVAC, Fire, Wiring)12
-
Security and Attacks39
-
Cloud and Virtualization13
-
Troubleshooting49
-
Network Monitoring7
-
Last Minute125
