220-1101 Networking Study Guide for the CompTIA A+ Core Series Exam

Protocols for Wireless Networking

You must be able to compare and contrast wireless networking protocols and what they have in common and where they differ.

Frequencies

The frequency of a wireless protocol refers to the audio range in which the technology broadcasts. The two operating frequencies for Wi-Fi are 2.4 GHz and 5 GHz. The frequency has an impact on transmission range and data throughput.

2.4 GHz—This relatively low frequency (compared with 5 GHz) has a greater transmission range because it passes through objects such as walls and floors better. On the negative side, throughput is slower and it is an open frequency range that other devices use. Devices like cordless phones and microwave ovens can interfere with it.

5 GHz—At this higher frequency, throughput is faster. On the negative side, the transmission range is shorter as the signal is attenuated by objects such as walls and floors.

Channels

Channels are different frequencies that are used for communications between the end-user device and the wireless access point. The 2.4 GHz range has 14 channels, but the top three cannot be used in North America, so the U.S. has 11 available channels. Devices will automatically select a channel, but if there seems to be interference, we can manually select another channel. The 5 GHz range also has channels, but there is more room in the RF spectrum at that range, so we never have to set those channels.

Regulations

The Federal Communications Commission (FCC) has defined 14 different 22 MHz communications channels but only allows for the use of the first 11 channels.

2.4 GHz vs. 5 GHz

There are 25 defined 20 MHz channels at 5 GHz, 24 of which can be used for Wi-Fi communications, while 2.4 GHz only has 14 defined channels, 11 of which can be used.

Bluetooth

Bluetooth allows devices to communicate over short distances (10 meters) in a personal area network (PAN). It is typically used to connect peripherals, such as headphones, to a laptop or smartphone. It is the IEEE 802.15.1 standard.

802.11

The Wi-Fi specification 802.11 is part of the IEEE 802 wireless networking standards. It is used for Wi-Fi communications. They all use the ethernet protocol and carrier sense multiple access with collision avoidance (CSMA/CA) media access method. The main characteristics that differentiate them are their operating frequencies, theoretical maximum data speed, and throughput.

a—5 GHz frequency, 54 Mbps maximum throughput, 120 meters range

b—2.4 GHz frequency, 11 Mbps maximum throughput, 140 meters range

g—2.4 GHz frequency, 54 Mbps maximum throughput, 140 meters range

n—5/2.4 GHz frequency, 600 Mbps maximum throughput, 250 meters range

ac (Wi-Fi 5)—5 GHz frequency, 6.5 Gbps maximum throughput, 140 meters range

ax (Wi-Fi 6)—5/2.4 GHz frequency, 9.6 Gbps maximum throughput, 140 meters range

Long-Range Fixed Wireless

A long-ranged fixed wireless connection is a point-to-point wireless technology that employs the use of directional antennas to send and receive network signals usually from 10 to 20 km.

Licensed

Licensed frequencies are frequencies whose use is granted by the FCC in the US.

Unlicensed

Unlicensed frequencies are frequencies that can be used by anyone, such as 2.4 and 5 GHz. The common use of these frequencies, however, often causes interference and can create susceptibility to eavesdropping.

Power

Power can be transmitted via long-range fixed wireless and is commonly known as wireless power transfer (WPT). Power is generated by the transmitting station and sent via microwave or laser light to the receiver who turns the transmission back into electricity.

Regulatory Requirements for Wireless Power

WPT technology is regulated by the FCC in the US.

Near-Field Communication (NFC)

Near-field communication (NFC) has a very short range of a few inches. It is used for contactless communications between devices that are right next to one another. The most common use today is for contactless payment systems.

Radio-Frequency Identification (RFID)

Radio-frequency identification (RFID) uses a radio signal to send information from an RFID tag with identifying information. This is commonly used to streamline the inventory of tracking applications.

Networked Host Services

You need to have a working understanding of the properties and purpose of network-delivered services in a client-server environment and know how to summarize them. Know the difference between a client application and a server application. Client applications request services from a server application.

Server Roles

You are expected to have a working understanding of the following network services. A server is not necessarily a stand-alone piece of hardware. A server is usually a process running in memory on a networked system that responds to requests from a remote client system.

DNS

Domain name system (DNS) servers resolve hostnames to IP addresses. Two public DNS servers are needed for an enterprise to host a website, with one DNS server acting as redundancy. Records of hostname IP address sets are held in a zone file. If the DNS address is not located in the zone file, it requests the information from a higher-level DNS server called the root server.

DHCP

A Dynamic Host Configuration Protocol (DHCP) server provides IP configuration information, such as an IP address, subnet mask, default gateway, and DNS server address, automatically to clients. The scope of a DHCP server contains the information that is permitted to be shared with a client.

Fileshare

A fileshare or file server is a central repository for the storage, management, and access of network files. A network can also use network-attached storage (NAS) for a file server.

Print Servers

A print server is a server that manages print requests and connects printers to a network.

Mail Servers

A mail server is responsible for sending, receiving, and managing emails. A mail server must be running a specialized server package, such as Microsoft Exchange, Sendmail, Postfix, or Exim, to be considered a mail server.

Syslog

The syslog server in a client-server model is responsible for collecting information obtained through system monitoring, such as login events or errors. Messages compiled in a syslog server include the facility code, the severity level, and a textual description of the logged events. Syslog servers are composed of three primary components: the listener, the database, and the management and filtering software.

Web Servers

A web server listens for incoming requests. The requests are executed by the web server and provide the requested content, including text, images, videos, and the running of scripts. Common web server platforms include Microsoft’s Internet Information Services (IIS) and Apache.

Authentication, Authorization, and Accounting (AAA)

An authentication, authorization, and accounting (triple A or AAA) server is an access control server that acts as a gatekeeper for critical network components. AAA servers are also known as domain controllers. Examples of AAA servers include remote access service (RAS), Remote Authentication Dial-In User Service (RADIUS), Terminal Access Controller Access-Control System Plus (TACACS+), and Kerberos.

Internet Appliances

An internet appliance is a device that aids in internet access and helps users access the internet safely.

Spam Gateways

A spam gateway, also known as an antispam gateway, is an internet appliance whose purpose is to block malicious emails from accessing the network.

Unified Threat Management (UTM)

Unified threat management (UTM) acts to centralize security management on a network. UTM typically provides packeting filtering and inspection, IPS, gateway antimalware, spam blocking, malicious website blocking, and application control.

Load Balancers

A load balancer is responsible for evenly distributing requests over servers to balance the system. Common load balancing configurations include identical, cross-region, and content-based load balancing.

Proxy Servers

A proxy server makes requests for resources on behalf of a client. The proxy server acts as an intermediary between the client and the target server.

Legacy/Embedded Systems

Legacy systems are older systems that for one reason or another have not been updated. It is usually due to essential applications that will not run on the updated platform. Embedded systems are devices other than computers that have computer technology running within. Like legacy systems, these may not be able to stay updated.

Supervisory Control and Data Acquisition (SCADA)

Supervisory control and data acquisition (SCADA) is an example of a critical legacy system category. A SCADA system is a high-level management system used to control manufacturing machines and processes, manage large-scale infrastructure settings, and run building components.

Internet of Things (IoT) Devices

An internet of things (IoT) device connects to the network through a central controller or coordinating device. Common examples of IoT devices include smart devices such as thermostats and home automation and security devices.