2.2/2.3 Wireless Techs./Network ServicesCompTIA A+ 220 -1201

What organization defines wireless networking standards?

Wireless networking standards are defined by the Institute of Electrical and Electronics Engineers (IEEE) through the IEEE 802.11 committee.

How are modern Wi-Fi versions named?

Modern Wi-Fi versions are also referred to by generation names:

• IEEE 802.11n ==> Wi-Fi 4

• IEEE 802.11ac → Wi-Fi 5

• IEEE 802.11ax → Wi-Fi 6 / Wi-Fi 6E

• IEEE 802.11be → Wi-Fi 7

What is (RFID) used for?

Radio-frequency identification

Wireless technology used for identification and tracking.

Common uses:

• Access badges

• Inventory tracking

• Animal microchips

A reader sends radio energy to a tag, and the tag returns its ID.

What frequencies does IEEE 802.11 Wi-Fi use?

Wi-Fi operates on:

• 2.4 GHz

• 5 GHz

• 6 GHz

Some standards support multiple bands.

What are Wi-Fi channels?

Channels are groups of frequencies defined by the Institute of Electrical and Electronics Engineers.

• Used to separate wireless signals

• Non-overlapping channels reduce interference

What does Wi-Fi bandwidth refer to?

Bandwidth is the amount of frequency spectrum used by the signal.

Common channel widths:

• 20 MHz

• 40 MHz

• 80 MHz

• 160 MHz

Larger bandwidth → higher speeds.

What is **Bluetooth used for?

Short-range wireless communication for devices like:

• Headsets

• Speakers

• Keyboards / mice

Uses 2.4 GHz ISM band and typically works up to ~10 meters.

What is Near-field communication (NFC)?

Very short-range wireless communication based on RFID.

Common uses:

• Contactless payments

• Mobile wallets

• Bluetooth pairing

• Access cards

Supports two-way communication and encryption.

What does a Domain Name System (DNS) server do?

A DNS server translates domain names into IP addresses and vice versa.

What does a Dynamic Host Configuration Protocol (DHCP) server do?

Automatically assigns network configuration to devices, including:

• IP address

• Subnet mask

• Default gateway

• DNS server

Common on home routers, while enterprise networks often use redundant DHCP servers.

What is a network file share?

A centralized storage location on a network where users can store and access files.

Used for things like:

• Documents

• Spreadsheets

• Videos

• Images

What protocols does a network file share use?

• Server Message Block (SMB)

• Apple Filing Protocol (AFP)

Users interact with files normally (copy, delete, rename) while the system handles the protocol behind the scenes.

What protocol do file servers commonly use?

• Server Message Block (SMB) - TCP 445

Used for file sharing in Windows networks.

What is a print server?

A server that manages printers and print jobs for devices on a network.

Ways it can exist:

• Software running on a computer connected to a printer

• Built directly into a network printer

What does a mail server do?

A server that sends, receives, and stores email.

Mail servers typically require 24/7 availability.

What is Syslog used for?

A standard system for centralized logging of messages from network devices and servers.

What protocol is used for centralized logging of events?

• Syslog — UDP 514

Collects logs from network devices.

What does a web server do?

A web server responds to requests from web browsers and delivers web pages.

Pages can be:

• Static – stored files sent to the browser

• Dynamic – generated in real time

Web pages are usually written in:

• HyperText Markup Language (HTML) or HTML5

Web server Protocols

• Hypertext Transfer Protocol (HTTP) – TCP 80

• HTTPS – TCP 443

What is an authentication server?

A server that verifies user identities before granting access to resources.

Often used in enterprise environments with systems like Microsoft Active Directory.

These servers are usually:

• Redundant

• Highly available

• Critical infrastructure

Authentication Server’s purpose (2 things)

• Centralized login management

• Controls access to network services

What is a database server?

A server that stores and manages structured data in tables.

Purpose: store and retrieve large amounts of organized data efficiently.

How is data accessed in a database server?

Data is accessed using Structured Query Language (SQL).

Examples:

• Microsoft SQL Server

• MySQL

How is data stored in database servers?

• Data stored in rows and columns (like a spreadsheet)

• Often a relational database where tables are linked through relationships

What does a Network Time Protocol (NTP) server do?

Provides accurate time synchronization to devices on a network.

• Devices periodically synchronize their clocks

Accurate time is important for: (5 things)

• authentication

• encryption

• log timestamps

• backups

• system coordination

What protocol does a time server use?

• Network Time Protocol (NTP) — UDP 123

Synchronizes clocks across network devices.

Identity & Access Servers

• DHCP server → gives devices IP addresses

• Domain Name System (DNS) server → converts names to IPs

• Authentication server → verifies login credentials

Resource Servers

These provide things users actually use.

• File server → shared files

• Print server → shared printers

• Database server → stores structured data

• Mail server → handles email

Infrastructure Servers

These keep the network running smoothly in the background.

Examples:

• Network Time Protocol (NTP) server → synchronizes time

• Syslog server → central log collection

• Web server → delivers web applications

What is a spam gateway?

A server or service that filters unwanted email before it reaches users.

It works at the network gateway, filtering email before it reaches the mail server or inbox.

What is an all-in-one security appliance?

A device that combines multiple network security functions into one system.

Often called:

• Unified Threat Management (UTM)

• Next-generation firewall

Common features include:

• Firewall

• Intrusion Detection System / Intrusion Prevention System (IDS/IPS)

• Malware inspection

• Spam filtering

• URL/content filtering

• VPN endpoint

• Bandwidth shaping

Some models may also include:

• Router

• Switch

• CSU/DSU

What does a load balancer do?

A load balancer distributes network traffic across multiple servers.

Purpose:

• Prevents one server from being overloaded

• Improves performance

• Provides fault tolerance

Example:

Instead of:

Users → 1 web server

You get:

Users → Load Balancer → Server 1
                       → Server 2
                       → Server 3

If a server fails, traffic is automatically sent to the others.

Commonly used in:

• **Web server farms

• **Database server farms

What is a proxy server?

A proxy server is an intermediary between a client and the internet.

How it works:

Client → Proxy → Router → Internet server

Steps:

1. Client sends request to proxy

2. Proxy sends the request to the website

3. Website responds to proxy

4. Proxy returns results to the client

Useful features:

• Access control (block websites)

• Caching (store frequently accessed content)

• URL filtering

• Content scanning

Proxy benefits

• Security (hide clients)

• Control (access restrictions)

• Acceleration (caching)

• Logging (monitoring)

• Protection (content filtering)

What are Supervisory Control and Data Acquisition (SCADA) and Industrial Control Systems (ICS)?

SCADA / ICS are computer systems used to monitor and control industrial equipment and processes.

Used in industries such as:

• power generation

• manufacturing

• oil and gas refining

• water treatment

• transportation and logistics

Key features:

• Real-time monitoring and control

• Often spread across multiple locations

• Collects data from machines and sensors

• Sends commands to control equipment

Security requirement:

• Highly segmented networks

• Usually no direct internet access

What protocols are used by mail servers and their ports?

Send mail:

• Simple Mail Transfer Protocol (SMTP) — TCP 25

Receive mail:

• Post Office Protocol 3 (POP3) — TCP 110

• Internet Message Access Protocol (IMAP) — TCP 143

What protocols do print servers use and ports?

• Server Message Block (SMB) - TCP 445

• Internet Printing Protocol (IPP) - TCP 631

• Line Printer Daemon (LPD) - TCP 515

What is a legacy system?

A legacy system is an older computer system or technology that is still in use.

Characteristics:

• Often outdated hardware or software

• Still used because it performs a critical function

• May be difficult or expensive to replace

Examples:

• old business databases

• outdated operating systems

• industrial control computers

What is an embedded system?

An embedded system is a computer built into a device to perform a specific function.

Characteristics:

• Purpose-built device

• Usually no direct access to the operating system

• Performs a single dedicated task

Examples:

• alarm systems

• door access control systems

• time card systems

• printers

• smart appliances