Chapter 6: Networking

Static IP Addresses

A static IP address is one that a user manually configures for a device instead of having it assigned by DHCP. The reason that it's called static is that it doesn't change in the way a dynamic IP address does. This is what you need if you want to give a device a fixed address that can be easily accessed in the future. Users often use static IP addresses for things like file servers, network printers, running a printer server, or using a remote access program.

Cellular

A technology that uses cellular radio signals to establish connectivity to the internet. (T-Mobile, Verizon cellular internet)

Wi-Fi

A technology that uses radio signals to connect a device to an access point.

Status Codes

300-399 (Redirection): 100-199 (Informational): Informational status codes are temporary responses that let the requesting computer know that the message has been received. They're almost always immediately followed by another status code.Example: 101 means switching protocols. The user has asked the server to change to a different protocol, such as ftp, and the server is agreeing with the request. 200-299 (Success): A success code means that the client's request was understood and accepted.Example: 200 means OK. When you successfully go to a website, the server responds with code 200, which means the request was successful. 300-399 (Redirection): Redirection codes mean that the user will be redirected to a different resource, usually after the user does some additional action such as clicking a link.Example: 301 means moved permanently. All requests to this URL should be redirected to a new URL. This is common when a company changes names or rebrands itself. 400-499 (Client Errors): Client error codes means the user seems to have made a mistake.Example: 404 means not found. The server sends a 404 error when someone requests a file that doesn't exist. 500-599 (Server Errors): Server error codes indicate that the web server itself is malfunctioning.Example: 503 means service unavailable. This code is sent when a server is either overloaded with too many requests or down for maintenance.

Virtual Private Network (VPN)

A tool that allows internet users to create a secure, private network when using a public internet connection. A VPN masks a user's IP address to make actions untraceable and shields the user's data from others.

Hypertext Transfer Protocol (HTTP)

A protocol that governs the transfer of web content between computers.

DHCP Servers

A DHCP server is a network server that uses DHCP to assign IP addresses and subnet masks. It's vital that every computer on a network have a unique IP address so conflicts don't arise. If a network didn't have a DHCP server, the network administrator would have to manually set up every client who wanted to join the network. This would be a cumbersome and inefficient process, especially if they were dealing with a large network. When a network computer comes online, it sends a message to the DHCP server to request an IP address. The server then automatically offers to lease an IP addresses to network computers in the order that it receives them. The network computer accepts the lease offer and connects to the network.

Local Area Network (LAN)

A LAN is a group of connected computers that are physically close, usually in the same building. The computers in your office, school, or library are probably connected to each other on a LAN. LAN has the word "local" in the title because it's a network of connected devices localized in a single physical location, such as in a single office building, private residence, or other business. Just because it only covers a single physical location doesn't mean that a LAN can't be quite large. A LAN can range in size from a few devices in someone's home to thousands of users in a large company under the same roof. LANs can connect devices by Ethernet cables (a wired connection) or over Wi-Fi (a wireless connection). There are many benefits to setting up a LAN, including the following: 1) Devices can share a single Internet connection 2) Devices can print to shared printers 3) Devices can share files with one another 4) Devices can access or control each other if needed

SOHO

A LAN that only services a home or small business, it is sometimes referred to as a Small Office Home Office, or SOHO.

Coaxil Cable

A cable that provides transmission on a network through its inner wire in the form of electrical signals. The wire is made up of four different components: an inner conductor, an insulator made of flexible PVC, a metallic shield, and a plastic jacket coating.

Twisted Pair Cable

A cable that transmits data through electrical signals and provides better signals because of its eight unique plastic-coated copper wires that are twisted into four pairs.

Fiber Optic Cable

A cable that uses light pulses to transmit data instead of electrical signals.

Default Address Class

A class designation (A through E) that specifies a default subnet mask value which defines the default network address portion of the IP address.

Domain Name System (DNS)

A protocol that helps internet users and network devices discover other devices using a human-readable hostname instead of numeric IP addresses.

Router

A router's job is to send signals from one network to another. When you send an email, the signal travels through a wire or radio signal to your network's router. The router sees that data is addressed to a different network and forwards it to the ISP. The ISP's router looks at the data, sees where it's supposed to go, and sends it to the router on the network where the recipient's mail server is stored.

Subnet Mask

A value given to an address in a subnetted network that tells a computer which numbers are part of the network or subnet address and which are part of the host address.

HTTP Method

A command that tells the server what the user wants to do. The most common methods are POST, GET, PATCH, and DELETE. These methods are used for CRUD operations which stand for Create, Read, Update, and Delete. The Hypertext Transfer Protocol (HTTP) - Is used to identify resources and transfer hypertext pages on the World Wide Web.

Client-Server Model

A computing model where computer servers supply network and computational services (such as email, file sharing, online gaming, and VoIP) that are consumed by client computers.

Wall Jack

A device, usually located on a building wall, that provides a port (usually RJ-45) where a network cable can be connected. On the hidden side of a wall jack is wiring to a patch panel or to a network device.

Dynamic IP Addresses

A dynamic IP address is one that's handed out by DHCP. It's called dynamic because it can change from time to time. Dynamic IP addresses are used for most home networks because they're the most cost-effective way for internet service providers (ISPs) to assign IP addresses. Instead of always giving the same IP address to your home computer, DHCP pulls from a pool of IP addresses it has at its disposal. Periodically, DHCP can assign you a new IP address when the lease for the current one expires.

IEEE 802 Standards

A family of standards that mostly dictate with how data is transferred between hosts in a local area network (LAN). The IEEE 802 family of standards deals mostly with local area networks, and the protocols for wireless networks are found in section 11. A wireless local area network that conforms to 802.11 standards is called a Wi-Fi network. As technology has improved, so have 802.11 protocols. Over time, they have improved in several areas.

IEEE 802.11 Standards

A family of standards under the 802 standards that dictate how data is transferred between hosts in a wireless network. Popular 802.11 standards are 802.11a, 802.11b, 802.11g, 802.11n, and 802.11ac. 802.11 contains security protocols, which encrypt transmitted data. The first security protocol was called WEP, or Wired Equivalent Privacy. This protocol eventually became outdated and was replaced with WPA, or Wi-Fi Protected Access. This, in turn, was upgraded to WPA2, which is the most secure and is used today by virtually all secure Wi-Fi networks to provide encryption and authentication services

Client

A host on a network that consumes network services.

Server

A host on a network that provides network services.

Network Hosting

A method of delivering applications by installing them on the local network.

Dynamic Host Configuration Protocol (DHCP)

A network management protocol that assigns IP addresses on a network. It is part of the larger set of built-in networking protocols known as TCP/IP.

Metropolitan Area Network (MAN)

A network that covers a larger geographical area than a LAN, but is usually as large as a WAN. The term generally refers to smaller networks that are connected throughout a city into one larger, centralized network. A MAN is kind of network that covers a larger geographical area than a LAN, but isn't usually as large as a WAN. The term is generally used with smaller networks connected throughout a city into one larger, centralized network. Large cities such as London and Geneva have created MANs, but large universities also refer to their networks as MANs due to their size and complexity.

Bus Topology

A network topology in which all the devices are connected to each other by a single central cable. Downside: If two computers try to send a message at the same time, their data will collide on the wire and be corrupted; this can lead to much slower transmission times.

Star Topology

A network topology in which devices are not connected to each other but rather to a centralized device called a switch. The switch's job is to route data to the correct destination host. The switch also prevents data from colliding. Star tolpologies are easy to implement.

Ring Topology

A network topology in which each host is connected to two other hosts in a circle. Fine for small networks; difficult to implement for large networks.

Mesh Topology

A network topology where each device on the network has a point-to-point connection to every other device on the network. This topology was previously just theoretical until the rise of smart devices and wireless connecting media which allowed devices to communicate directly to every other device through one network adapter in each device using radio signals and wireless network adapters.

Private Network

A private network can be accessed only by computers inside the network. This is essential for businesses that want employees to have access to the files they need for work and want to provide a high level of data protection.

Hypertext Transfer Protocol Secure (HTTPS)

A protocol that combines HTTP with the Secure Sockets Layer (SSL) protocol to securely transfer web content between computers. Hypertext Transfer Protocol Secure (HTTPS) - Provides secure transfer over the internet. One of the biggest downsides of HTTP is that it transmits data as plain text. An attacker could intercept the signal during transmission and read the sensitive information it contains. When websites need to send or receive data securely, they use HTTPS, which combines HTTP with the Secure Sockets Layer (SSL) protocol. SSL encrypts data so unauthorized parties can't understand the data even if they manage to intercept it.

Virtual LAN (VLAN)

A virtual LAN (VLAN) is a logical grouping of computers based on a switch port. Most screened segments, also known as demilitarized zones (DMZs), are created using a VLAN. You can configure multiple VLANs with varying security requirements on one switch. This keeps the cost down. Although devices connect to the same switch, they cannot see other devices that are configured to a separate VLAN. All communication between separate VLANs must go through the router. When setting up VLANs, keep in mind: VLAN membership is configured by assigning a switch port to a VLAN. A switch can have multiple VLANs configured on it, but each switch port can be a member of only one VLAN. The one exception is described below. VLANs can be defined on a single switch or configured on multiple interconnected switches. When interconnecting switches, a high bandwidth backbone segment is used. The backbone segments are typically between the router and the internet, as well as between the switches themselves. With multiple switches, each switch can be configured with the same VLANs. The devices on one switch can communicate with devices on other switches if they are members of the same VLAN. A trunk port is used to connect two switches together. In a typical configuration with multiple VLANs, workstations in one VLAN cannot communicate with workstations in other VLANs. To enable inter-VLAN communication, use a router or an OSI Layer 3 switch. Using VLANs, you can create multiple IP broadcast domains on a switch. Each VLAN is in its own broadcast domain. Broadcast traffic is sent only to members of the same VLAN. A screened subnet, (demilitarized zone) is a segmented network (or subnet) that sits between the private network and an untrusted network, such as the internet. Typically: Firewalls allow traffic that originates in the secured internal network into the screened subnet and through to the internet. Traffic that originates in the screened subnet (low-security area) or the internet (no-security area) should not be allowed access to the intranet (high-security area). Because screened subnets can be challenging to access for management and administrative tasks, a server, or jumpbox, can be implemented to provide a tightly controlled access method, or jumping point, for administrators.

Mail Server

Mail servers provide email service to a network. In many ways, they're like virtual post offices. They store incoming mail and send outgoing messages, either to users on the same network or on other networks around the world.

Transmission Control Protocol (TCP)

An important protocol in the internet protocol suite that enables two hosts to establish a connection and exchange data.

User Datagram Protocol (UDP)

An important protocol in the internet protocol suite that is generally used when speed in transmission is more important than accuracy since the sending computer doesn't verify that the packets were correctly received.

Speed

Another major difference between protocols is how fast they can transmit data. This is measured in bits per second. The table below compares the maximum transfer rates of several versions of the 802.11 protocol. Link: https://www.dropbox.com/s/txtpam4n25eqxor/Screen%20Shot%202021-11-02%20at%209.06.59%20PM.png?dl=0

Ethernet

Any wired network that conforms to the 802.3 protocols developed and maintained by the IEEE.

802.11g and 802.11a

Are IEEE wireless standards that specify transmission speeds of up to 54 Mbps.

Firewall

As amazing as the internet is, it's full of malicious people and software that you want to keep away from your computer. A firewall checks each bit of data (called a packet) that tries to enter your network. If the firewall decides the packet's safe, it passes it along. Otherwise, it drops or rejects the packet. This firewall function is called packet filtering.

Bluetooth

Bluetooth is a technology used to create wireless connections between computers and devices. Bluetooth uses radio signals to connect devices at a short range, usually no more than ten meters. Bluetooth is a wireless networking standard that uses 2.4 GHz radio waves. These are the same type of radio waves used with 802.11 wireless networking, so radio transmission can go through walls (not limited to line-of-sight connections). Bluetooth uses ad hoc connections between devices. Infrared uses red spectrum light waves and is limited to line-of-sight transmissions. Ad hoc connections (temporary connection)

Radio Frequency ID (RFID)

RFID, can be used for tracking objects. There are two types of RFID, passive (does not require power) and active (does require power). Passive RFID tags can be embedded in labels and stickers for tracking in manufacturing and shipping. Fixed infrastructure RFID readers can scan data up to 100 feet. Handheld readers can often exceed 50+ feet. Common uses of RFID technology include placing RFID labels on products (such as clothing) to prevent theft and monitoring progress of participants in a race.

Access Point

Conceptually, an access point (AP) works in a similar way to a switch; it recognizes the device that should receive the signal, then forwards the data to where it needs to go. The main difference is that APs use Wi-Fi technology to connect devices to the network wirelessly; a switch uses wires. In an enterprise network, the AP supports more devices than those used in a SOHO.

POST

Create; The POST method requests that a web server accept data from the user, usually to store it in a database. POST is used to submit completed web forms, including social media posts and comments.

Network Type Summary

Local Area Network (LAN): - Fewer devices - Limited geographical area - Share files - Share printers - Share control of devices Metropolitan Area Network (MAN): - Many devices - Larger geographical area such as a city or campus - Similar to a LAN Wide Area Network (WAN): - Connected LANs - Very large geographical area - Uses VPNs - Share applications - Share firewalls

Digital Subscriber Line (DSL)

DSL is a better alternative to dial up. It uses the same phone connection as dial up; however, DSL uses the high-frequency ranges that voice calls don't use. This means that the data connection doesn't use the phone connection. With DLS, a phone call can be made while someone is connected to the internet. DSL is also considered to be asymmetric (ADSL). This means that the bandwidth and bit rate is faster while downloading data than it is while uploading data. Download speeds can reach up to about 24 Mbps while the upload speed are around 1.4 Mbps. (ATT Dial Up)

Database Server

Database servers store databases, which are large repositories of organized data. Clients on the network can send queries to the database server, which returns specific information about the data. Clients can also use queries to add, remove, or change data as appropriate.

DELETE

Delete; DELETE requests tell the server to delete the specified resource.

Interference

Dense material (such as steel) or electronic devices (such as cordless phones) that reduce or block Wi-Fi signals.

Subnetting

Dividing a network into smaller subnets.

Web Server

Every site you've visited on the World Wide Web, including this one, has been hosted on a web server. Web servers store web pages as hypertext documents. Whenever a webserver gets a request for one of its pages, it transmits the appropriate file to the requester using HTTP.

Fiber Optic

Fiber networks use fiber optic cables to send signals with light instead of electricity. This has a few considerable advantages. Light isn't vulnerable to electromagnetic interference. It has potential for much higher speeds than DSL or cable. The downside is that fiber networks are expensive to build. Due to costs, many areas don't have access to a fiber connection. As you begin to work with or consider using fiber optics, you should be familiar with the following terms: Fiber to the Home (FTTH) is also called fiber to the premises (FTTP). FTTH uses fiber cable from the source to your home or business. A good example of this is Google Fiber which is part of the Access division of Alphabet Inc. Fiber to the Curb (FTTC) brings the fiber cable from the source to a pole or closet that houses the mounted communications device. FTTC can serve many customers within about 1,000 feet. FTTC uses twisted pair copper wires (telephone cabling) and Very High Bit Rate DSL (VDSL). FTTC is less expensive than FTTH. (Google)

File Server

File servers provide network access to shared disk storage. They make it easier to share and backup files from a central location. When a shared drive is set up on a file server, clients can access the network drive from their file system more easily by associating it with a unique letter, such as G: or N:. This is called drive mapping. The shared disk storage can consist of internal drives, drives directly attached to the server, or through a Network attached storage (NAS) device. NAS devices contain one or more hard drives that users can access over the network. NAS drives can be used for file sharing, backups, and even streaming media. Each NAS is controlled by some type of internal firmware (often programmed in Linux). You can plug some NAS devices into an Ethernet port, while other NAS devices can be accessed wirelessly. Since the NAS is separate from a computer, it is managed from a Web connection.

Home Router

For a small network, such as a SOHO, most people buy a single router. These are usually called wireless (Wi-Fi) routers. However, they typically combine features of several of the above devices into one device.

Gaming Server

Gaming servers keep track of events in multiplayer video games. Most online games have players simultaneously sending inputs via their mouse and keyboard (or controller). The game server receives all inputs and retransmits them to the other players. This makes the game play out in real time for everyone involved.

Logical Address

Logical addresses are assigned by software and, as such, can be changed. They include two parts: the network address and the host address. The network address specifies the network segment (also called a subnet). All devices on the same network segment share the same logical network address. The logical host address identifies a specific host on the network. Each device must have a unique logical host address. The most common types of logical addresses are those assigned by the IP protocol and are called IP addresses. IP addresses combine the logical network and logical host addresses into a single address. An example IP address is: 192.168.1.1.

IP Address Classes

IP addresses use default classes that include a default subnet mask value. The class defines the default network address portion of the IP address. Table 2: IP Address Classes Link: https://www.dropbox.com/s/c8v5jaioqrni97r/Screen%20Shot%202021-11-02%20at%208.21.39%20PM.png?dl=0 The IP address 192.168.6.11 is an example of a Class C address that uses a default mask of 255.255.255.0. With this address, the network address is 192.168.6.0, and the host address is 11. Be aware that the address range from: 0.0.0.0 to 0.255.255.255 is reserved for broadcast messages to the current network. 127.0.0.0 to 127.255.255.255 is reserved for loopback addresses to the local host.

Internet Protocol (IP)

In a small network with a few computers, a printer, and a server, each device would have its own IP address. The format for an IP address is four numbers between 0 and 255, separated by periods (e.g., 192.168.1.1). This is known as a dotted decimal notation. Each segment of the address is called an octet. This is because in binary, each section is represented by eight digits, from eight zeros all the way up to eight ones, which is the same as 255 in decimal. In summary, an IP address: Is a 32-bit binary number represented as four octets (four 8-bit numbers). Each octet is separated by a period. Can be represented in one of two ways: Decimal (e.g., 131.107.2.200). In decimal notation, each octet must be between 0 and 255. Binary (e.g., 10000011.01101011.00000010.11001000). In binary notation, each octet is an 8-digit number. Includes both the network address and the host address. Uses a subnet mask to differentiate the network and host addresses.

3G to G5

In between 2G and 3G, is the General Packet Radio Services/Enhanced Data Rates for GSM Evolution (GPRS/EDGE). It is used on top of GMS and was a lead up to 3G. GPRS is packet-based, meaning that the data is broken up into small blocks and transmitted over various channels. GPRS supports a download speed of 114Kbps. EDGE is slightly faster than GPRS with a download speed over two-times faster at 384Kbps. 3G networks first appeared around 2001. They were the first networks that enabled a mobile broadband connection. This created cellular networks that had speeds from 200 KBps up to a few Mbps. This was a huge leap forward. 3G networks were developed using the following standards: Evolved High Seed Packet Access (HSPA+) - A mobile network technology that offers upload data speeds up to 42 Mbps and download speeds between 3.5-14 Mbps. CDMA2000/Evolution Data Optimized (EV-DO) - An evolution of the CDMA2000 (IS-2000) standard. It supports an upload speed of 1.8 Mbps and a download speed of 3.1 Mbps. 4G networks appeared around 2009 and provided even greater speeds of up to hundreds of megabits per second. It is based on the Long Term Evolution (LTE) standard; it is supported by both CDMA and GSM providers. Currently the average LTE download speed is about 13.5 Mbps but could reach up to 150 Mbps once provider's networks are improved. LTE Advanced (LTE-A) improves on LTE and can usually provide a download and upload speed of two to three times faster than LTE. 5G networks appeared around 2020 and provided even greater speeds (up to 20 GB at peak rates). 5G networks: Have lower latency, making them more responsive to commands. Can handle about one million devices per 1 square kilometer (about .4 square miles). Are bringing about the full potential of the Internet of Things (IoT), in which devices communicate seamlessly with each other in real time.

Dial Up

In the early days of the internet, most home computers used a dial-up connection. To get internet access, the computer would make a phone call to the ISP. Just like a regular voice call, this call was an analog signal. As the computer dialed in, you could hear the sound of the data. A device called a modulator/demodulator (modem) sat between the computer and the phone line. The modem converted digital data from the computer into analog sound data for the phone line. For data coming to your computer from the internet, analog data from the phone was converted to digital data for your computer. The main disadvantages to dial-up connections were that they were extremely slow and they tied up the phone line.

Internet Message Access Protocol (IMAP)

Internet Message Access Protocol (IMAP) - Is a much more common receiving protocol. With IMAP, email messages stay saved on the remote mail server. This way, people can access their emails from multiple devices, such as a home computer, a work laptop, and a smartphone.

Internet Service Provider (ISP)

Internet Service Providers (ISP) are organizations that provide many services for accessing and using the Internet.

Satellite

Many ISP service types require physical wires to transmit data. However, those who live in rural areas don't have a wired network to connect to. Fortunately, they can connect to the internet via a satellite connection. By aligning a satellite dish (antenna) to an orbital satellite hovering above the equator, you can get internet access from nearly anywhere in the world. The main downside is latency. Because the data has to travel to space and back, it can take a few seconds longer to exchange data. While this may not seem like much, it makes a big difference for real-time applications like online gaming and video conferencing. The satellite dish is usually installed by the ISP with a coaxial cable going from the dish to a Digital Video Broadcast Satellite (DVB-S) modem, which can be installed in a computer using an expansion card. In some cases, you can use an external modem attached to the computer using a USB connection. (Dish, Direct TV)

Modem

Modem is short for modulator/demodulator. Signals that arrive at your network from an Internet Service Provider (ISP), whether through fiber, cable, or phone line, can't be directly understood by your computer. Instead, the signal passes through a modem that translates it into a series of electrical ones and zeros that travel through a copper wire to your computer. To upload data to the internet, the modem does the opposite, turning ones and zeros into light, cable, or phone signals.

Near Field Communications (NFC)

NFC uses specially encoded tags that respond in a specific way when scanned by a radio frequency reader (peer-to-peer). NFC is a subset of RFID. As the name implies, NFC only works within a close range (about two inches). If you've ever held your smartphone near a scanner to pay for an item in a store, you've used NFC. Another common use of NFC is to get product information. By scanning the NFC code, you can obtain the details about a particular item or product.

Attenuation

One of the features of a radio wave is attenuation. As a radio signal travels away from its point of origin, the signal becomes weaker. If you've ever listened to the radio in your car as you've driven out of town, you've experienced attenuation first hand. One of the drawbacks of higher-frequency bands is that they have more attenuation, and therefore cover less distance.

Cable

Phone lines aren't the only way ISPs can send signals. They can also send them over television cables (as part of the Cable Access TV-CATV service). Cable internet is generally provided by the same company that sends cable TV signals to your house. Since cable companies can already send multiple TV channels on the same cable, they can easily add a few extra channels for data. This is sometimes called a Hybrid Fiber Coax (HFC) because fiber optic is used from the source to an area near the destination. Then the coax cable is used the rest of the way. Cable connections require a cable modem to receive the signal from a coaxial cable. The modem converts the signal to digital data, typically transmitted over copper Ethernet cables. The standard used for CATV are set by the Data Over Cable Service Interface Specifications (DOCSIS). DOCSIS has several specifications, such as DOCSIS 1.0, 2.0, 3.0, and DOCSIS 3.1. Each version provides more features and better download speeds. For example v3.0 supports about 1.2 Gbps download speeds while 3.1 can support up to 10 Gbps download speeds. (Spectrum or Charter)

Post Office Protocol 3 (POP3)

Post Office Protocol 3 (POP3) - Is one of two protocols used to receive email. When an email client uses POP3, it grabs messages from the remote server, downloads them to the local client, then deletes them from the server.

Public Network

Public networks can be accessed freely by anybody. The most important public network is the worldwide system of interconnected networks called the internet.

GET

Read; The GET method is used to retrieve data from a web server. Whenever you visit a website, your computer sends a GET request to the site's server.

IEEE 802.11 Encryption Protocols

Security protocols that govern how data in a wireless network is secured by encryption. Examples of these protocols are Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA), and WPA2. Below is a brief summary of each of these encryption standards: WEP is an optional component of the 802.11 specifications and was deployed in 1997. WEP was designed to provide wireless connections with the same security as wired connections. This encryption standard has many weakness and should never be used unless there is no other option (which may be the case with older equipment). WPA is the implementation name for wireless security based on initial 802.11i drafts. It was deployed in 2003. WPA was intended as an intermediate measure to take the place of WEP while a fully secured system (802.11i) was prepared. It uses Rivest Cipher (RC4) with a 128-bit key and a 48-bit initialization vector (IV) for encryption. It also uses the Temporal Key Integrity Protocol (TKIP) for encryption, making it more secure than WEP. WPA2 is the implementation name for wireless security that adheres to the 802.11i specifications and was deployed in 2005. This implementation is built upon the idea of Robust Secure Networks (RSN). Like WPA, it resolves the weaknesses inherent in WEP and replaces both WEP and WPA. One of the main differences between WPA and WPA2 is the use of the Advanced Encryption Standard (AES) with a 128-bit key and a 48-bit initialization vector for encryption, which is more secure than TKIP.

Creating a Network

Several key components must be in place for two computers to communicate over a network. 1. Network media must be used to connect the computers. This is usually done with copper wiring or radio signals. 2. A network interface must be installed in each computer to connect it to the network media. 3. Network protocols must be configured on each computer. The same protocol must be configured on all computers in the network for them to communicate with each other.

Switch

Similar to the way a router transfers data between networks, switches transfer data between devices within a network. Every computer on the network is connected to the switch. Whenever a computer sends a signal or a signal comes in from the router, the switch looks at the data. If it recognizes the receiving computer as another device on the switch, it sends it directly to that computer. If it doesn't recognize the data, it sends it to the router. A switch in a Small Office Home Office (SOHO) usually has anywhere from four to eight RJ-45 ports. A switch in the enterprise environment has 20 or more ports. Switches in the enterprise environment can be interconnected. This allows them to provide support for hundreds of connections.

Simple Mail Transfer Protocol (SMTP)

Simple Mail Transfer Protocol (SMTP) - Is used to send email. When you send a message, SMTP routes it through the internet to its destination mail server. SMTP is used by all email systems that use the internet.

Application

The Application layer contains high-level protocols used by processes (applications) running on a host for network communications. The Application layer integrates network functionality into the host operating system and enables network services. The Application layer does not include specific applications that provide services, but rather provides the capability for services to operate on the network.

Internet

The Internet layer is responsible for forwarding packets through multiple networks. This process is called routing and is done by encapsulating the packets into internet datagrams. The Internet layer manages host addressing and routing decisions to identify how packets traverse networks. Protocols that reside at the Internet layer include: Internet Protocol (IP) - As one of the main protocols in the TCP/IP suite, the IP protocol uses logically-assigned IP addresses to uniquely identify networks and network hosts. This helps in the routing of the packets between each host and network. Address Resolution Protocol (ARP) - This protocol links an IP address to a host's physicals address (MAC address). For example, when you use a browser to access a site, you use the IP address (a number not too difficult to remember or use). However, to communicate with the host, the process needs to know the MAC address (hardware address) found on the interface card or device. ARP discovers the MAC address for you. Internet Control Message Protocol (ICMP) - This protocol supports the TCP/IP suite. It's main job is to send error messages and other operational information to let the systems know if the data was transferred successfully or if there was an error during transmission. It is used by network devices, including routers. Internet Group Management Protocol (IGMP) - This protocol is used by hosts and adjacent routers to establish multicast group memberships. IGMP is an integral part of IP multicast and allows the network to direct multicast transmissions only to hosts that have requested them.

Link/Network Interface

The Link layer is responsible for describing the physical layout of the network and how messages are electrically transmitted. It is used to move information between hosts by controlling how individual bits are transmitted and received on the network medium. The Link layer converts the data to be transmitted into frames by adding a Link layer header that includes physical device addressing information. Each frame processed by the Link layer includes the source MAC address and the destination MAC address. The Link layer then converts the frames into bits for transmission across the network media. The Link layer corresponds to the functions of the Physical and Data Link layers of the OSI model.

Registered Jack 45 (RJ-45) Interface

The RJ-45 interface is much more common in today's networks. These jacks have eight pins and are a little wider than RJ-11 connectors. RJ-45 is used to create a wired connection between a computer and a network. It is most often used to connect computers with Ethernet cables.

Registered Jack 11 (RJ-11) Interface

The Registered Jack 11 interface (RJ-11) has four pins and a clip to hold the plug into a wall socket. RJ-11 is used to connect to a telephone line. In a DSL network, this interface connects the modem to the wall jack. Many all-in-one devices that perform such services as printing, scanning, and faxing also have a RJ-11 connection. In these devices it is used for the faxing service.

Transport

The Transport layer is responsible for error checking and reliable delivery. In the transport layer, each application protocol is identified by a port number. Protocols that are associated with the Transport layer include: Transport Control Protocol (TCP) - Adds a header to each IP packet. The TCP header helps the receiving computer to assemble the packets into the correct configuration once the entire file is downloaded. The headers also allow the sending and receiving computers to verify with each other that each packet was received correctly. User Datagram Protocol (UDP) - Is generally used when speed in transmission is more important than accuracy, such as streaming audio or video. Like TCP, UDP adds a header to each packet. However, unlike TCP, the sending computer doesn't verify that the packets were correctly received. This makes transmissions happen much faster but allows transmission errors.

Downlink

The data being transferred from the ISP to your computer.

Uplink

The data being transferred from your computer to the ISP.

Twisted Pair Category

The different types of twisted pair cabling that are defined by the several aspects of a cable including its transmission specifications and intended use. Common categories include Cat 5e and Cat 6.

1G and 2G

The first wireless networks were 1G (1st generation) wireless. The next upgrades to these networks were known as 2G, 3G, 4G, and G5. Each new network generation is incompatible with previous versions. 1G was an analog cellular network that became available around 1979. It was able to transmit only voice signals. The first 2G standard was known as the Global System for Mobile Communications (GSM). This generation introduced the first digital cellular networks. It was first launched in 1991 and is still used in many places. Key points are: It provided only the transmission of voice signals. Unlike 1G, it allowed for data encryption. GSM was used in the United States by AT&T and T-Mobile and was also used internationally. A key feature of GSM is the SIM (Subscriber Identity Module) card. SIM cards are still commonly used to store the user subscription and phone boot information. This card can then be moved from mobile device to mobile device. Another 2G format is the Interim Standard 95 (IS-95), also known as cdmaOne. (CDMA stands for code division multiple access.) Unlike GSM, the mobile device is managed by the provider not the SIM.

2G and 3G

The first wireless networks were 1G (1st generation) wireless. The next upgrades to these networks were known as 2G, 3G, 4G, and G5. Each new network generation is incompatible with previous versions. 1G was an analog cellular network that became available around 1979. It was able to transmit only voice signals. The first 2G standard was known as the Global System for Mobile Communications (GSM). This generation introduced the first digital cellular networks. It was first launched in 1991 and is still used in many places. Key points are: It provided only the transmission of voice signals. Unlike 1G, it allowed for data encryption. GSM was used in the United States by AT&T and T-Mobile and was also used internationally. A key feature of GSM is the SIM (Subscriber Identity Module) card. SIM cards are still commonly used to store the user subscription and phone boot information. This card can then be moved from mobile device to mobile device. Another 2G format is the Interim Standard 95 (IS-95), also known as cdmaOne. (CDMA stands for code division multiple access.) Unlike GSM, the mobile device is managed by the provider not the SIM.

Network Cable

The network cabling connects the computer to the wired network. One end of the cable connects to the RJ-45 port on the computer. The other end connects to the RJ-45 port in the wall jack.

Network Interface

The network interface provides an RJ-45 port into which a network cable can be connected. On desktop computers, this port is usually found on the back. On notebooks and laptops, it is usually found on the side of the system.

IP Version 6

The number format described above is called IP version 4. It works great, with one small problem: as more devices have connected to the internet, all available IP addresses have been used. To solve this problem, the internet is transitioning into a new format called IP version 6. IPv6 addresses are expressed as 32-character hex numbers. IPv4 has about four billion potential addresses. IPv6 has trillions (340 undecillion, a number equal to 1 followed by 36 zeros).

Physical Address

The physical address of a device is also called the media access control (MAC) address. MAC addresses are burned into the read-only memory of every network interface, such as wireless network adapters and network interface cards. This makes it virtually impossible to change the device's MAC address. An important feature of MAC addresses is that they are globally unique. No two network interfaces in the world have the same MAC address. An example of a MAC address is 00-09-5B-36-C2-93. The MAC address is sometimes shown as a group of four hex values (e.g.,0009.5B36.C293). Note that the MAC addresses are in hexadecimal form. Therefore, a MAC address can consist only of the numbers 0-9 and the letters A-F. MAC addresses are a 48-bit binary number. However, you will always work with MAC addresses as a 12-character hex number. MAC addresses are typically composed of six groups of two hexadecimal digits separated by hyphens or colons. The first six characters of any MAC address are used to identify the manufacturer of the device; the last six identify the network interface. By using these two number sets, the manufacturer and the interface, no two network interfaces will ever have the same MAC address. Wireless networks are often configured to allow or reject client connections based on the hardware address. This is called MAC address filtering.

Hotspot/Tethering

The process of providing access to a computer through the mobile device's cellular connection.

Local Installation

The traditional method for delivering applications by installing them on individual desktop computer systems.

Network Topology

The way hosts are connected to each other in a network.

comparing the different 802.11 standards

Today, most wireless networks use either 802.11n or 802.11ac. The 5 GHz frequency provides 24 channels that do not overlap. 2.4 GHz only has 3 channels that do not overlap. Even though 5 GHz bands suffer from greater attenuation and consequently cover less distance, the significantly improved performance of 802.11n and particularly 802.11ac make them better standards in most scenarios. Bluetooth is a wireless networking standard that uses 2.4 GHz radio waves. These are the same type of radio waves used with 802.11 wireless networking, but Bluetooth has a maximum transfer rate of 1 Mbps and is used primarily for ad-hoc or impromptu connections between two devices. A typical example is a set of Bluetooth headphones that connects to a laptop computer.

PATCH

Update; A PATCH request tells the server to make a change to an existing resource, such as editing a social media comment.

Wide Area Network (WAN)

WANs are networks of interconnected LANs across a large geographical location. A WAN can cover a city, a state, a country, or even the entire world. WAN stands for wide area network, which means that it's made up of a larger geographical area than a LAN. In fact, it connects multiple LANs to create a much larger network. For example, if you have a company that has a headquarters and branch offices spread across different cities, each branch will have its own LAN, and all these company LANs will be connected into the larger WAN. A router is usually used to make the connection between a LAN and a WAN, but sometimes dedicated telecommunication lines are used as well WANs provide many advantages, such as allowing all users in a company to use the same applications, firewalls, and resources. This is beneficial because otherwise each of these things would have to be installed on individual machines. This would end up being much more time consuming and expensive. Many WANs are used in conjunction with a virtual private network (VPN). A VPN allows users in remote locations to use the Internet to connect to a WAN and access all the network resources as though they were in their company's main office or whatever central location was set up. The VPN keeps the network private through data encryption so that you have to log in in order to access the contents.

Electromagnetic Interference

When an electrical current passes through any kind of copper wire, that creates an electromagnetic field just outside the wire.

WPA2

Wi-Fi Protected Access 2 (WPA2) provides encryption and authentication for wireless networks. MAC address filtering allows or rejects client connections based on the hardware address. The SSID is the network name or identifier. A wireless access point (called an AP or WAP) is the central connection point for wireless clients. A firewall allows or rejects packets based on packet characteristics (such as address, port, or protocol type).

Frequency

Wi-Fi signals are sent using radio frequencies. Some standards, like 802.11b and g, use a 2.4 GHz band. This band has eleven channels. Unfortunately, most of these channels overlap with each other. The only non-overlapping channels are 1, 6, and 11. With only three usable channels, it was common for devices using the same network to fight over bandwidth and interfere with each other. To solve this, newer protocols, such as 802.11n and ac, started using a 5 GHz band, which has many more non-overlapping channels.

Service Set Identification (SSID)

Wireless devices use the SSID (Service Set Identification) to identify the network name. All devices on a wireless network use the same SSID.