Chapter 1 Networking Concepts - OSI, Cloud, Ports, Media, Topologies, IPv4, and Use Cases (N10-009)

A comprehensive set of Q&A flashcards covering OSI layers, networking appliances, cloud concepts, common ports and protocols, transmission media, topologies, IPv4 concepts, and modern use cases as presented in the lecture notes.

How many layers does the OSI Reference Model have and what is its purpose?

Seven layers; a conceptual framework to understand network interactions and promote interoperability by separating functions into layers.

What is Layer 1 (Physical) responsible for in the OSI model?

Physical transmission of data; hardware, cables, switches, and signaling that carries raw bits.

What is Layer 2 (Data Link) responsible for in the OSI model?

Node-to-node data transfer, error detection/correction in the physical layer, and framing; divided into MAC and LLC sublayers.

What does the MAC sublayer do in the Data Link layer?

Manages access to the physical medium and MAC addressing for multiple nodes on a network.

What does the LLC sublayer do in the Data Link layer?

Provides multiplexing and flow/error control and interfaces with network layer protocols.

What are the responsibilities of Layer 3 (Network)?

Logical addressing and routing of packets; determines best path and handles forwarding and congestion.

What are the responsibilities of Layer 4 (Transport)?

Reliable end-to-end data transfer; error correction, flow control, and segmentation.

What does Layer 5 (Session) manage?

Setup, maintenance, and termination of sessions; coordinates dialog between applications.

What is the role of Layer 6 (Presentation)?

Translation, encryption, and compression of data between application and network formats.

What is the role of Layer 7 (Application)?

Interface between user applications and network services; defines protocols for services like file transfer and web access.

What is a Physical vs a Virtual appliance in networking?

Physical appliances are dedicated hardware devices; virtual appliances run as software on virtual machines.

Where does a router operate in the OSI model and what does it use to forward packets?

Layer 3 (Network); uses routing tables and IP addresses to forward packets.

What security features do routers provide?

Firewalls and VPN support.

Where does a Layer 2 switch operate and how does it forward data?

Layer 2 (Data Link); forwards based on MAC addresses and creates separate collision domains.

What is a Layer 3 capable switch and what can it do?

A multilayer switch that operates at both data link and network layers and can route between subnets/VLANs.

What is a firewall?

A network security device that blocks or allows traffic based on configured rules.

What is the difference between an IPS and an IDS?

IDS passively monitors and alerts; IPS actively blocks or prevents threats based on rules and signatures.

What is the purpose of a load balancer?

Distributes inbound traffic across multiple servers to improve reliability and performance.

What is a proxy server used for?

An intermediary between a client and the internet; can cache content, enforce access, and filter traffic.

What is NAS and what protocols does it typically support?

Network-Attached Storage; centralized file storage on a network; supports NFS, SMB/CIFS, and AFP.

What is a SAN?

Storage Area Network; a dedicated high-speed network for block-level storage to improve availability and performance.

What is an Access Point (AP)?

Networking device that allows wireless devices to connect to a wired network; extends wireless coverage.

What is a Wireless LAN Controller (WLC)?

Manages wireless access points centrally, including configuration, security policies, and guest access.

What is a Content Delivery Network (CDN)?

Globally distributed proxies and data centers that cache content to reduce latency and improve access.

What is a VPN?

A technology that creates a secure, encrypted connection over an insecure network like the internet.

What is QoS used for?

Managing and prioritizing network traffic to ensure performance of critical applications.

What does Time to Live (TTL) indicate in IP packets?

The maximum time or number of hops a packet can traverse before being discarded.

What is Network Functions Virtualization (NFV)?

Decouples network functions from hardware and runs them as software on virtual machines or containers.

What is a Virtual Private Cloud (VPC)?

An isolated network space in a public cloud with control over IP ranges, subnets, and gateways.

What are Network Security Groups?

Virtual firewall for a VPC that controls inbound and outbound traffic by rules.

What are Network Security Lists?

Subnet-level filters that provide stateful or stateless traffic control in cloud environments.

What is a Cloud Gateway?

Intermediary that connects cloud environments with other networks to enable secure data transfer.

What is an Internet Gateway in cloud networking?

Bridge between a VPC and the internet, enabling internet access for VPC resources.

What is a NAT Gateway?

Allows private subnets to access the internet while preventing inbound connections to those instances.

What are cloud connectivity options mentioned?

VPN and private-direct connections to a cloud provider.

What are the public, private, and hybrid deployment models?

Public: services over the internet; private: dedicated to one organization; hybrid: mix of both.

What are the main cloud service models SaaS, IaaS, PaaS, and DaaS?

SaaS delivers software over the internet; IaaS provides virtualized computing; PaaS provides a platform for development; DaaS delivers desktop as a service.

What does scalability mean in networking and cloud computing?

The ability to grow resources easily and cost-effectively to handle increased work.

What does elasticity mean in cloud computing?

Automatic scaling of resources up or down to match demand.

What is multitenancy?

Single software instance serves multiple tenants with isolated data per tenant.

What does 802.11a stand for and what band/rate does it use?

Wi-Fi 802.11a; 5 GHz band; up to 54 Mbps.

What does 802.11b stand for and what band/rate does it use?

Wi-Fi 802.11b; 2.4 GHz band; up to 11 Mbps.

What does 802.11g stand for and what are its characteristics?

Wi-Fi 802.11g; 2.4 GHz band; up to 54 Mbps; backward compatible with 802.11b.

What does 802.11n (WiFi 4) offer?

WiFi 4; up to 600 Mbps with MIMO; operates in 2.4 and 5 GHz bands.

What does 802.11ac (WiFi 5) offer?

WiFi 5; operates in the 5 GHz band; multi-gigabit speeds with wider channels and more spatial streams.

What does 802.11ax (WiFi 6) introduce?

WiFi 6; higher data rates (up to ~9.6 Gbps theoretical); OFDMA and BSS Coloring for efficiency.

What is the general purpose of fiber-optic cabling?

Transmits data using light for higher speeds and bandwidth over long distances.

What is single-mode fiber used for?

Long-distance transmission with a single path of light to minimize attenuation and dispersion.

What is multimode fiber used for?

Short-distance transmission with multiple light paths; lower cost and easier to work with.

What are DAC cables used for?

Direct Attach Copper cables; short-range, cost-effective copper connections.

What is Twinaxial cabling used for?

Short-range, high-speed differential signaling typically used in data centers.

What is RG-6 coax used for?

Coaxial cable used for TV, satellite, and broadband internet with good shielding.

What are SFP, SFP+, QSFP, and QSFP+ modules?

Compact, hot-pluggable transceivers; SFP up to 1 Gbps, SFP+ up to 10 Gbps, QSFP up to 40 Gbps, QSFP+ up to 40 Gbps+.

What are common fiber connectors: SC, LC, ST, MPO?

SC: square connector with push-pull; LC: small form-factor; ST: bayonet; MPO: multi-fiber high-density.

What is RJ-11 used for and what is its pin configuration?

Telephone interface; typically 6P4C; supports up to four wires.

What is RJ-45 used for and what is its pin configuration?

Ethernet connector; 8P8C; used to connect devices for LANs.

What is the F-type connector used for?

Coaxial RF connections for cable and satellite TV, broadband, and signals.

What is a network topology?

The layout of network elements like links and nodes that affects performance and reliability.

What is mesh topology and its main advantage?

Every node connects to many others; high availability and redundancy; no single point of failure.

What is a hybrid topology?

Combination of two or more topologies to leverage their advantages.

What is a star topology?

All nodes connect to a central hub; easy to manage but a single point of failure at the hub.

What is spine and leaf architecture used for?

Two-layer data center design with leaf (access) and spine (backbone) switches for scalability and low latency.

What is the three-tier hierarchical network model?

Core layer handles high-speed backbone; Distribution layer aggregates and controls WAN; Access layer connects end devices.

What is collapsed core architecture?

Merges core and distribution layers to simplify design and reduce costs; suitable for smaller networks.

What is North-South traffic in data centers?

Traffic between the data center and external networks (clients/servers outside the data center).

What is East-West traffic in data centers?

Traffic within the data center, such as server-to-server or VM-to-VM communications.

What is APIPA and its IP range?

Automatic Private IP Addressing; range 169.254.0.1 to 169.254.255.254; used when DHCP fails.

What is RFC 1918 addressing?

Private IP ranges for internal networks: 10.0.0.0/8, 172.16.0.0–172.31.255.255, 192.168.0.0/16.

What is the loopback address for IPv4 and IPv6?

IPv4: 127.0.0.1; IPv6: ::1.

What is CIDR notation and VLSM?

CIDR replaces classful addressing with prefix lengths; VLSM allows subnetting with different sizes.

What is the CIDR notation example and meaning (192.168.1.0/24)?

First 24 bits are the network portion.

What are Class A addresses and their default mask?

Class A: first octet 1-126; default mask 255.0.0.0; ~16.7 million hosts per network.

What are Class B addresses and their default mask?

Class B: first octet 128-191; default mask 255.255.0.0; ~65,534 hosts per network.

What are Class C addresses and their default mask?

Class C: first octet 192-223; default mask 255.255.255.0; up to 254 hosts per network.

What are Class D and Class E addresses used for?

Class D: 224-239; multicast; no default host/network split. Class E: 240-255; experimental; no default split.

What is SDN and how does it differ from SD-WAN?

SDN decouples network control from forwarding; SD-WAN applies SDN principles to WAN for dynamic path selection.

What is Zero-Touch Provisioning in SD-WAN context?

Remote deployment where devices fetch configuration from a central location with minimal manual setup.

What does VXLAN do in data center networks?

Extends Layer 2 segments over Layer 3 networks; enables many virtual networks and large-scale deployments.

What is Layer 2 Encapsulation in VXLAN?

Encapsulates Ethernet frames inside UDP packets to create virtual networks across physical networks.

What is Zero Trust security?

Security model that never trusts by default and requires continuous verification of identity and posture.

What is policy-based authentication in Zero Trust?

All users and devices must be authenticated and continuously validated before access.

What is authorization in Zero Trust architecture?

Dynamic, context-aware access control that grants permissions per session based on identity and risk.

What is the principle of least privilege?

Grant only the minimum access rights needed to perform a task.

What are SASE and SSE?

SASE combines WAN and security services in the cloud; SSE focuses on security services delivered from the cloud.

What is Infrastructure as Code (IaC)?

Managing and provisioning infrastructure with machine-readable configuration files and code.

What is automation in IaC used for?

Automates infrastructure deployment and configuration to improve consistency and speed.

What are playbooks, templates, and reusable tasks in IaC?

Reusable code artifacts that standardize deployment steps and configurations.

What is configuration drift in IaC?

Deviation of the live environment from the intended configuration, which IaC helps prevent.

What is the role of upgrades in IaC?

Upgrades are managed via code revisions and are version controlled and reversible.

What are dynamic inventories in IaC?

Automated discovery and management of resources based on real-time data.

What is the role of source control in IaC?

Tracks changes, enables collaboration, and maintains integrity of infrastructure code.

What is the meaning of a central repository in source control?

Single source of truth for code changes to enable team collaboration.

What is conflict identification in source control?

Automated detection of conflicts when multiple contributors change the same code.

What is branching in source control used for?

Allows development of new features or experiments without affecting the main line.