CompTIA Network+ Exam Review

Exam Overview

Clients

Devices that users use to access the network (e.g., workstations, laptops, tablets)

Servers

Provide resources to the network (e.g., email servers, file servers)

Hubs

Older technology connecting devices but not commonly used due to limitations

Switches

Smarter hubs that ensure security and efficient bandwidth utilization

Wireless Access points (WAPs)

Enable wireless devices to connect to a wired network using radio frequency waves

Routers

Connect different networks, make intelligent forwarding decisions based on IP addresses

Firewalls

Security barrier between internal network and the internet, monitor and control traffic

Load Balancers

Distribute network/application traffic across servers, preventing bottlenecks

Proxy Servers

Act as intermediaries between user devices and the internet, enhancing security and privacy

Intrusion Detection System (IDS)

Detect unauthorized access or anomalies

Intrusion Prevention System (IPS)

Detect and take action to prevent intrusion

Controllers

Manage flow control in software-defined networking (SDN), offering flexibility and efficiency

Network-attached Storage (NAS) Devices

Dedicated file storage systems providing data access to authorized clients

Storage Area Networks (SANs)

High-speed networks for consolidated block-level data storage, enhancing accessibility

Media

Physical materials for data transmission (e.g., copper cables, fiber optic cables)

Wide Area Network (WAN) Links

Connect networks over large areas (e.g., between cities), essential for global connectivity

Key Takeaway

Understanding these network components is crucial for efficient and secure data transmission in information technology, aiding in network design, management, problem-solving, and security implementation

Client/Server Model

■ Utilizes a dedicated server for centralized access to files, scanners, printers, and resources

■ Easy administration and backup due to a central server

Benefits to Client/Server Model

● Centralized administration

● Easier management

● Better scalability

Drawbacks to Client/Server model

● Higher cost

● Requires dedicated hardware and specialized skillset

Peer-to-Peer Model

■ Direct sharing of resources among peers (laptops, desktops)

■ Difficult administration and backup due to dispersed files on different machines

Drawbacks

● Redundancy

● Complex management

● Scalability issues

■ Usefulfor low-cost setups, exemplified by Napster a decade ago

Benefits to Peer-to-Peer Model

● Low-cost

● No specialized infrastructure or hardware

Drawbacks to Peer-to-Peer Model

● Decentralized management

● Poor scalability for large networks

Personal Area Network (PAN)

■ Smallest network type

■ Covers about 10 feet or less

■ Examples are Bluetooth and USB

■ Connection within arm's reach

Local Area Network (LAN)

■ Common in office buildings

■ Limited distance

● Up to 100 meters

● CAT5 cabling

■ Can use WiFi (IEEE 802.11) or Ethernet (IEEE 802.3)

■ Examples include Office, school, and home

Campus Area Network (CAN)

■ Building-centric LAN

■ Spans numerous buildings in an area

■ Covers several miles

■ Examples are College campuses, business parks, military bases

Metropolitan Area Network (MAN)

■ Connects locations across the entire city

■ Larger than CAN ● Up to 25 miles

■ Examples are City departments, multiple campuses in a city

Wide Area Network (WAN)

■ Connects geographically disparate internal networks

■ Large geographic coverage

● Across states, countries, or globally

■ Can consist of lease lines or VPNs.

■ Examples are Internet, private connections between offices across the country

Important Standards

Network Topology

■ Refers to the arrangement of elements in a computer network

■ Includes links, nodes, clients, and servers

Diagram Types

■ Physical Topology

● Describes physical cabling and device connections

● Represents real-world layout using floorplans

■ Logical Topology

● Describes how data flows in the network

● Focuses on the logical connection rather than physical placement

Point-to-Point Topology

● Direct connection between two devices

● Simple, reliable for small-scale connections

● Not scalable

● Used in WAN connections for remote offices

Ring Topology

● Circular data path with each device connected to two others

● Unidirectional flow prevents collisions

● Creates a single point of failure situation unless there are redundant connections for failover

● Common in FDDI (Fiber Distributed Data Interface) for long-distance fiber optic networks.

Bus Topology

Star Topology

Hub-and-Spoke Topology

Mesh Topology

Infrastructure Mode

Ad Hoc Mode

Wireless Mesh

■ Use Cases for Wireless Mesh

● Post-disaster scenarios

● Humanitarian assistance missions

● Combining microwave, satellite, cellular, and Wi-Fi for reliable and redundant networks

○ Satellite for long distances

○ Microwaves for medium ranges

○ Wireless for short distances

Datacenter

Any facility composed of networked computers and storage that businesses and other organizations use to organize, process, store, and disseminate large amounts of data

Core Layer

● Houses high-performance routers, merging geographically separated networks

● Backbone of the network

Distribution/Aggregation Layer

● Provides boundary definition through access lists and filters

● Defines policies for the network at large

Access/Edge Layer

● Connects endpoint devices using regular switches

● Used to ensure the packets are converted to frames and delivered to the correct end point devices

Collapsed Core

● Network architecture where the core and distribution layers are merged into a single layer

● Creates a two-tiered core

● Simplified architecture for medium to small datacenters

● May not be suitable for larger and more complex networks

Spine and Leaf Architecture

North-South Traffic

● Traffic that enters (Southbound traffic) or leaves (North traffic) data center from a system outside

East-West Traffic

● Dataflow within a datacenter

● Example: In a spine and leaf architecture, all data flow between servers is considered east-west traffic

● Prevalent with SDN, virtualization, and converged networks

Open Systems Interconnect Model (OSI)

■ Developed in 1977 by the International Organization for Standardization

■ OSI is a reference model

● Used to categorize the functions of a network

● Useful for troubleshooting

Layers

Names of data as it flows through the OSI model

Layer 1 (Physical)

■ First layer of the OSI model where transmission of bits across the network occurs and includes physical and electrical network characteristics

■ Data type occurs as bits

● Binary bits represented as a series of 1s and 0s

Transition Modulation

■ Switching between levels to represent 1 or 0

● Copper Wire (Cat5/Cat6) – Uses voltage (0V for 0, +5V/-5V for 1)

● Fiber Optic Cable– Uses light (on for 1, off for 0)

Connector Standards

■ RJ-45Connector– Used in CAT5/CAT6 cables

■ Wiring Standards

● TIA/EIA-568A

● TIA/EIA-568B

■ Crossover cables– TIA/EIA-568A on one end, and TIA/EIA-568B on the other end

■ Straight-through cables– TIA/EIA-568B on both ends

Asynchronous Communication

● Start and stop bits for out-of-sync data transmission

Synchronous Communication

● Real-time communication using a common time source

Broadband

● Divides bandwidth into separate channels (e.g., cable TV)

Baseband

● Uses all frequency of the cable all the time (e.g., telephone)

Multiplexing

■ Involves taking some limited amount of resource and using it more efficiently

● Allows multiple people to use a baseband connection at the same time

Time Division Multiplexing (TDM)

● Allocates dedicated time slots

Statistical Time Division Multiplexing (StatTDM)

● Dynamically allocates time slots based on when people need it

Frequency Division Multiplexing (FDM)

● Divides the medium into channels

Data Link Layer (Layer 2)

■ Responsible for packaging bits from Layer 1 into frames and transmitting them across the network
■ Performs error detection and correction, identifies devices using MAC addresses, and provides flow control

MAC Address (Media Access Control Address)

■ A means for identifying a device physically and allowing it to operate on a logical topology ■ A unique 48-bit physical addressing system is assigned to every network interface card (NIC) produced

● Written in hexadecimal numbers

● First 24 bits– identify the manufacturer

● Remaining 24 bits– identify the specific device

■ Crucial for logical topology– identifying devices on the network

Logical Link Control (LLC)

■ Provides connection services and acknowledges message receipt, ensuring controlled data flow

■ Most basic form offl ow control

● Limits data sent by a sender and prevents receiver overwhelm

■ Uses a checksum to detect corrupted data frames

Layer 3 (Network Layer)

■ Concerned with routing and forwarding traffic using logical addresses

IP Variants - common logical addressing schemes

Packet Switching (Routing)

● Data is divided into packets and then forwarded

● Most commonly used method

Circuit Switching

● A dedicated communication link is established between two devices

Message Switching

● Data is divided into messages which may be stored and then forwarded

Route Discovery and Selection

Connection Services at Layer 3

Augment Layer 2 services

■ Involves flow control

● Prevents sender from overwhelming the receiver

Packet reordering

● Ensures data packets arrive and are reassembled in the correct order

Internet Control Message Protocol (ICMP)

Layer 4 (Transport Layer)

■ Dividing line between the upper layers and the lower layers of the OSI model

■ Upper Layers

● Transport

● Session

● Presentation

● Application

Segments

■ Data Type in Transport Layer

TCP (Transmission Control Protocol)

● Connection-oriented protocol that is a reliable way to transport segments across the network

● With acknowledgement

● Uses Three-Way Handshake

○ SYN–synchronization

○ SYN-ACK–synchronization- acknowledgement

○ ACK–acknowledgement

● Windowing for flow control

● Used for all network data that needs to be assured to get to its final destination

Segment–datatype for TCP

UDP (User Datagram Protocol)

● A connectionless protocol that is an unreliable way to transport segments (datagram)

● Used for audio and visual streaming

● No three-way handshake and less overhead

● No acknowledgment or retransmission
Datagram–datatype for UDP

Windowing

■ Allows clients to adjust the amount of data in each segment during transmission

■ Optimize throughput and bandwidth

■ Open or close window based on retransmissions

Buffering

■ Occurs when devices allocate memory to store segments if bandwidth is not readily available

■ Buffer

● Temporary storage for segments

■ Prevents overflow by clearing segments

Layer 5 (Session Layer)

■ Manages sessions, ensuring separate conversations to prevent data intermingling

Setting Up Session

■ Checking of user credentials and assigning numbers to sessions to help identify

Maintaining Session

■ Continuous data transfer between parties

■ If connection breaks, it will require re-establishment

■ Includes acknowledgement of data

Tearing Down a Session

■ Ending a session once communication goals are achieved

■ Mutual agreement or one party disconnects

Layer 6 (Presentation Layer)

■ Responsible for formatting data for exchange and securing it through encryption

Data Formatting

Encryption

Using to scramble data in transit to keep it secure and provide data confidentiality

Transport Layer Security (TLS)

● Ensures secure data transfer

● Creates an encrypted tunnel, protecting sensitive information

Control how ASCII Text is displayed on the screen

● HTML

● XML

● PHP

● JavaScript

Different ways of displaying text using ones and zeros

● ASCII

● Unicode

● EBCDIC

Different graphical representations of 1s and 0s

● GIFs

● JPEGs

● TIFFs

● SVGs

● PNGS

1s and 0s formatted to create watchable videos

● MP4s

● MPEGs

● MOV

Scrambles data to provide confidentiality and security during transit and storage

● TLS

● SSL(Secure Sockets Layer)

Layer 7 (Application Layer)

■ Provides application-level services where users communicate with the computer

■ Focus on lower-level applications

● File transfer

● Network transfer

Application Services

Service Advertisement

■ Applications send announcements to other devices on the network

■ Devices advertise the services they offer

● Printers and file servers managed by Active Directory

● Self-advertising devices like wireless printers

Email Applications (Layer 7 Protocols)

● POP3

● IMAP

● SMTP

Web Browsing (Layer 7 Protocol)

● HTTPS

● HTTP

Layer 7 Protocol (DNS)

Domain Name Services