What marks a deterministic network?
Network access should be very organized and orderly.
What is an example for a deterministic approach?
The token-ring system where (like in a classroom) a token is given to a device, as long as it has the token, this device is allowed to send and all other devices are quiet.
How does a contention-based network work?
It works more like a conversation between friends at a table. Every sender tries to find a gap and send when the others are silent. As there are no set restrictions, collision can occur with this method.
What are the advantages/disatvantages of a contention based network?
Pro:
- Less overhead (no token needed to pass)
- Better usage of the bandwith
Con:
- Can become way more chaotic
- Collision will appear
What does Ethernet use to counter the issue with collision?
CSMA/CD:
Carrier Sense Multiple Access with Collision Detection
What happens when a collision occurs with CSMA/CD?
- Both devices stop transmitting
- Both devices generate a random number (Random Backoff Timer)
- The number represents a timer in milliseconds, after the timer hits 0, the devices listens if any other device is transmitting and if not it retransmitts the data
What is a collision domain? What differences does the use of a hub compared to a switch make?
Each are of the network, that shares a single segment.
For example 4 devices that are connected to a hub, are all on the same collision domain. This also means they can all only use half-duplex because otherwise they would hear themselves.
If those 4 devices are connected to a switch tho, each port on that switch is its own collision domain, allowing all 4 devices using full-duplex.
What are the 3 types of hubs?
- Passive hub: Just repeats the signal
- Active hub: Repeats and amplifies the signal, allowing more than the 100m limit twisted pair cables pose
- Smart hub: Active hub with SNMP capabilities
Hubs are basically dead and no longer used tho.
What is a bridge and what layer is it on?
Its a Layer 2 device. It has an internal MAC table that allows it to only forward traffic if the destination MAC address is on the other side of the bridge.
What is a switch and which layer is it on?
Its on Layer 2.
A switch is basically a multiport bridge or a hub that has a bridge on every single port. It connects multiple network segments. Each port is its own collision domain.
Everything on one switch is part of the same broadcast domain.
How does the MAC address resolution works with ARP?
Adress Resolution Protocol (when all MAC addresses are unknown):
1. PC1 (YY) wants to talk to PC4 (MAC: XX)
2. PC1 sends out an ARP saying i need to talk to MAC address XX
3. The switch gets it and now knows PC1 = YY, the ARP packet gets forwarded to all machines until one answers, “I am XX”, the switch saves the information PC4=XX
4. For every new connection the data can be send directly without disturbing the other devices on the network.
What is the main advantage of a router over a switch?
A router can separate broadcast domains.
What is a Layer3 Switch?
Its basically a combination of a router and a switch. It has routing capabilities and connects network segments but each port now is its own broadcast and collision domain.
Less efficient as a router.
What standard MTU sizes exist?
Wired Ethernet: 1500 bytes
Wireless Network: 1420 bytes
VPN: 1400 bytes
Jumbo Frames: 9000 bytes
What happens when a switch receives a frame with a destination MAC not in its CAM table?
It floods the frame out all ports except the incoming one.
What is the purpose of a VLAN?
It logically segments a network into separate broadcast domains for better security and management.
What type of traffic is reduced by VLANs?
Broadcast traffic.
What is a trunk port?
A switch port configured to carry traffic for multiple VLANs using tagging.
What is an access port?
A switch port assigned to a single VLAN, usually for end devices.
Why is Spanning Tree Protocol (STP) important?
It prevents switching loops and broadcast storms by blocking redundant paths.
What is a root bridge in STP?
The central switch chosen as the reference point for the spanning tree. Its chosen based on the lowes BID (Bridge ID: Priority Value + MAC)
What is port security on a switch?
A feature that restricts which MAC addresses can connect to a specific port.
What happens if a device with an unauthorized MAC address tries to connect to a port with port security enabled?
The switch can block traffic, shut down the port, or restrict access depending on configuration.
What is sticky MAC in port security?
A feature that allows a switch to dynamically learn and save MAC addresses on a port as if they were manually configured.
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Network Fundamentals20
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OSI Model23
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Ports and Protocols20
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Media and Connectors31
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Distribution Systems14
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Wireless Networks25
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Ethernet Switching28
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IP Addressing26
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Routing15
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Network Services16
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Wide Area Networks10
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Cloud and Datacenters20
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Network Security Fundamentals10
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Network Attacks12
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Logical Security13
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Network Segmentation14
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Network Monitoring15
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Orchestration and Automation10
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Documentation and Processes7
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Disaster Recovery8
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Troubleshooting Methodology5
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Troubleshooting Tools13
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Troubleshooting Physical Networks22
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Troubleshooting Wireless Issues12
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Ports18
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Extra Questions24
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Extra Questions 217
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Troubleshooting Network Services14
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Extra Questions 317
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Troubleshooting Performace Issues6
