Section 1: Networking Concepts Flashcards
What is Layer 1 in the OSI Model and what does it do?
Physical layer
How data travels physically by using cables etc
Cables, fiber, and the signal iteself
It involves hardware elements such as cables, switches, and electrical signals 4that transmit raw data bits over a network. It is how data physically travels from one device to another (through wires, fiber optics or radio waves).
What is Layer 2 in the OSI Model and what does it do?
Data Link Layer
How data moves between devices on the same network
Frame, MAC address, Extendted Unique Identifier (EUI-48, EUI-64, Switche
It uses MAC addresses to identify devices on the local network and helps prevent data collision by managing how multiple devices share the same network.
What is Layer 3 in the OSI Model and what does it do?
Network Layer
Decides where traffic goes and how it gets there
IP Address, Router, Pakcet
It uses IP address to identify devices and routers to forward data along the best route.
What is Layer 4 in the OSI Model and what does it do?
Transport Layer
Ensures reliable data transfer, error checking and flow control
TCP segment, UDP datagram
It uses protocols like TCP (for reliable, ordered delivery) and UDP (for faster, unordered delivery) to manage how data is sent and received, ensuring complete and accurate communication between devices.
What is Layer 5 in the OSI Model and what does it do?
Session Layer
Keeps track of active connections between devices
Control Protocols and tunnelling protocols
It keeps connections organized and on track, making sure devices can pick up where they left if needed. Control Protocols and tunnelling protocols use this.
What is Layer 6 in the OSI Model and what does it do?
Presentation Layer
Makes data readable
Application encryption (SSL/TLS)
Responsible for formatting and translating data so the application layer can understand it. It handles data encryption, compression, and conversion between different formats.
What is Layer 7 in the OSI Model and what does it do?
Application Layer
The layer we see
Your eyes
Common protocols at this layer include HTTP, FTP, DNS, POP3 and many others.
What is a Router and what layer of the OSI model does it operate at?
Purpose: Routes traffic between IP subnets.
OSI Layer: Layer 3 (Network Layer).
Connections: Connects diverse network types (e.g., LAN to WAN) using copper or fiber cables.
What is a Switch and what layer of the OSI model does it operate at?
Purpose: Forwards data using MAC addresses.
OSI Layer: Layer 2 (Data Link Layer).
Technology: Uses hardware bridging (ASIC - Application-Specific Integrated Circuit).
Design: Typically has many ports and advanced features for network connectivity.
What is a Firewall and what layer of the OSI model does it operate at?
Purpose: Filters traffic by port number or application.
Security: Encrypts traffic with VPNs between sites.
OSI Layer: Often operates at Layer 3 (can function as a router).
Features: Supports NAT (Network Address Translation) and dynamic routing.
What is IDS / IPS?
IDS (Intrusion Detection System): Monitors and alerts on suspicious activity.
IPS (Intrusion Prevention System): Blocks threats before they enter the network.
Purpose: Protects the network from unauthorized or malicious activity.
What is a Load Balancer?
Purpose: Distributes traffic load across multiple servers.
Usage: Ideal for large-scale implementations; invisible to the end-user.
Benefits: Provides fault tolerance, so server outages don’t impact service; allows fast recovery.
What is a Proxy and how does it work?
Purpose: Acts as an intermediary between users and the external network.
Function: Receives user requests, reviews them, and forwards them to the destination.
Uses: Supports caching, access control, URL filtering, and content scanning.
Types: Some proxies are transparent (invisible to the user); some applications need configuration to use a proxy.
NAS vs SAN
NAS (Network Attached Storage):
Shared storage on the network.
Uses file-level access: files are pulled across the network into system memory.
SAN (Storage Area Network):
Appears as local storage.
Uses block-level access: efficient for fast reads and writes.
Both: Require high bandwidth and may use isolated, high-speed network technologies.
What is an Access Point and what layer of the OSI model does it operate at?
Purpose: Extends a wired network to a wireless network.
Note: Not the same as a wireless router.
OSI Layer: Operates at Layer 2 (Data Link Layer).
What is a Wireless LAN Controller and what functions does it have?
Purpose: Centralized management of multiple access points.
Functions: Deploy new access points, monitor performance and security, configure and update settings, and report on access point usage.
Design: Usually proprietary, paired with specific access points for seamless integration.
What does CDN stand for and what does it do?
Content Delivery Network
Purpose: Speeds up data delivery to users.
How it Works: Uses geographically distributed caching servers, so users get data from a nearby server.
User Experience: Invisible to the end user.
What is a VPN and what does it do?
Virtual Private Network
Purpose: Secures private data over a public network.
Integration: Often built into firewalls.
Options: Available as hardware or software with specialized encryption.
What does QoS stand for and what is it?
Quality of Service
Purpose: Controls bandwidth and data rates.
Function: Prioritizes important applications over others for better performance.
Management: Configurable in settings of routers, switches, firewalls, or dedicated QoS devices.
What does TTL stand for and what does it do?
Time To Live
Purpose: Sets a timer (in hops or seconds) for data availability.
Function: Stops data from circulating indefinitely; used to drop looping packets or clear cache entries.
Applications: Helps prevent network loops and manage cache expiration.
What is TTL in IP, and why is it important?
TTL (Time To Live): A countdown built into data packets to prevent endless travel in network loops.
- Packets are data pieces that travel across networks.
- Hops refer to each router a packet passes through.
- TTL Countdown: Each hop reduces the packet’s TTL by 1.
- TTL Zero: If TTL reaches zero, the router drops the packet, stopping it from looping indefinitely.
What is NFV, and how does it benefit network infrastructure?
Network Function Virtualization
Purpose: Replaces physical network devices with virtual ones, managed via a hypervisor.
Functions: Provides routing, switching, load balancing, firewalls, and more—just like physical devices.
Advantages: Quick and easy deployment from the hypervisor.
Deployment Options: Can be deployed as virtual machines, containers, with fault tolerance, etc.
What is a VPC, and how is it typically secured and connected?
Virtual Private Cloud
Purpose: A pool of resources in a public cloud, commonly set up to support multiple application environments.
Connections: VPCs connect through a transit gateway (cloud router) to communicate with each other.
Security: Often secured with a VPN, as VPCs are typically on separate IP subnets.
How do VPC gateways help connect private and external resources in the cloud?
VPC Gateway: Connects internet users to cloud resources.
VPC NAT Gateway: Allows private cloud subnets to access external resources.
Security: External resources cannot initiate connections to the private cloud.
Network Security Lists vs. Network Security Groups
Network Security List:
- Broad rules for an entire IP subnet, applying to all devices in it.
- Easier to manage but lacks granular control.
Network Security Group:
- Specific rules for each device’s virtual NIC.
- More granular, requires more management, and provides better control.
- Best practice for cloud security.
What are the main Cloud Deployment Models?
Public: Accessible to anyone over the internet.
Private: Dedicated to a single organization; like a virtualized local data center.
Hybrid: Combines both public and private cloud environments.
