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In an information system, computer networks act like a complicated web, connecting devices, databases, and applications. They provide the communication channels that link everything together. A computer network is a collection of interconnected devices, such as computers, servers, and other hardware, that communicate and share resources with each other. This communication can occur over wired or wireless connections and allows for the exchange of data, information, and services among the connected devices. To efficiently and effectively use computers, you need to understand the concepts of connectivity, the wireless revolution, and communication systems. Additionally, you need to know the essential parts of communication technology, including channels, connection devices, data transmission, network architectures, and network types.
Communication is the process of sharing data, programs, and information between two or more computers. Applications include texting, e-mail, videoconferencing, and electronic commerce. Connectivity is a concept related to using computer networks to link people and resources. You can link or connect to large computers and the Internet, providing access to extensive information resources. Mobile devices like cell phones and tablets have brought dramatic changes in connectivity and communications. These wireless devices are becoming widely used for computer communication. Computer networks connect two or more computers. Some specialized network terms include:
• Node: any device connected to a network.
• Client: node requesting resources.
• Server: node providing resources.
• Directory server: specialized node that manages resources.
• Host: any computer system that provides access to its resources over a network.
• Router: a node that forwards data packets from one network to another network.
• Switch: node that coordinates direct flow of data between other nodes. Hub is an older device that directed flow to all nodes.
• NIC (network interface card): LAN adapter card for connecting to a network.
• NOS (network operating system): controls and coordinates network operations.
• Network administrator: network specialist responsible for network operations.
Communication systems transmit data from one location to another. There are four basic elements:
• Sending and receiving devices originate or accept messages.
• Connection devices act as an interface between sending and receiving devices and the communication channel.
• Data transmission specifications are rules and procedures for sending and receiving data.
• Communication channel is the actual connecting or transmission medium for messages.
Communication channels carry data from one computer to another. Communication channels are the routes or mediums through which information is transmitted between a sender and a receiver. These channels can take various forms: wireless and physical connections. Wireless connections do not use a solid substance to connect devices. Most use radio waves. WiMax (Worldwide Interoperability for Microwave Access) extends the range of Wi-Fi networks using microwave connections. Bluetooth transmits data over short distances; widely used for a variety of wireless devices. Wi-Fi (wireless fidelity) uses high-frequency radio signals; most home and business wireless networks use Wi-Fi. Microwave line-of-sight communication; used to send data between buildings; longer distances require microwave stations. Cellular uses cell towers to send and receive data within relatively small geographic regions or cells. Satellite uses microwave relay stations; GPS (global positioning system) tracks geographic locations. Infrared uses light waves over a short distance.
Physical connections use a solid medium to connect sending and receiving devices. Connections include twisted-pair cable (telephone lines and Ethernet cables), coaxial cable, and fiber optic cable.
The type of network determines the geographic scope and the scale of connections between devices. From small local setups to expansive global infrastructures, each network type serves distinct purposes based on its design and configuration. Types of network include:
• Local Area Networks (LANs): LANs are typically confined to a single building or a campus. They provide high-speed connectivity for devices within a limited area. (LANs) connect nearby devices. Ethernet is a LAN standard. These LANs are called Ethernet LANs. Home networks are LANs used in homes.
• Wireless LANs (WLANs) use a wireless access point (base station) as a hub. Hotspots provide Internet access in public places.
• Wide Area Networks (WANs): WANs cover larger geographic areas and connect multiple LANs. They span states and countries or form worldwide networks. The Internet is the largest wide area network in the world.
• Metropolitan Area Networks (MANs): MANs cover cities or large campuses and are larger than LANs but smaller than WANs. They connect multiple LANs within a city. (MANs) link office buildings within a city, spanning up to 100 miles.
• Personal Area Networks (PANs): PANs are short-range networks designed for connecting personal devices like smartphones, laptops, and wearables. (PANs) are wireless networks for Bluetooth headphones, cell phones, and other wireless devices.
• Campus Area Networks (CANs): CANs are networks that cover a specific campus or university and often consist of interconnected LANs.
Network devices are the hardware components that facilitate the transmission, reception, and management of data within a network. They serve various functions, from directing data traffic to providing access and security controls. Common network devices: Routers connect different networks and determine the best path for data to travel. Switches connect devices within the same network. They are essential for LANs. Hubs are older devices that simply broadcast data to all connected devices, lacking the intelligence of switches. Access Points (Aps) provide wireless connectivity in Wi-Fi networks, allowing devices to connect wirelessly to a wired network. Modems modulate and demodulate digital data to transmit it over analog communication channels, such as telephone lines or cable connections. Modulation is the name of the process of converting from digital to analog. Demodulation is the process of converting from analog to digital. Transfer rate is measured in megabits per second. There are three commonly used types of modem: A wireless modem is also known as a WWAN (wireless wide area network), DSL, and cable. Gateways connect different types of networks and translate between different network protocols. Network gateways connect networks to one another.
Connection Service
For years, large corporations have been leasing special high-speed lines from telephone companies. T1, T3 (DS3), and OC (optical carrier) lines provide support for very-high-speed, all digital transmission for large corporations. Cellular service providers support voice and data transmission using cellular networks. These mobile telecommunications networks have gone through different generations—1G, using analog radio signals; 2G, using digital radio signals; 3G, beginning of cell phones; 4G, using LTE (Long Term Evolution); and 5G, being developed.
Network Protocols
Network protocols are sets of rules and conventions that govern how data is formatted, transmitted, received, and acknowledged in a computer network. These protocols define the standards for communication between devices, ensuring that data can be successfully exchanged across the network. Protocols are rules for exchanging data. Packets are small parts of messages. Network protocols include:
• TCP/IP: The foundation of the internet, TCP/IP is a suite of protocols for data transmission and network communication.
• HTTP: The Hypertext Transfer Protocol is used for web browsing and requesting web pages.
• FTP: File Transfer Protocol is used for transferring files over a network.
• SMTP: Simple Mail Transfer Protocol is used for sending email messages.
• DNS: The Domain Name System translates domain names into IP addresses.
• DHCP: Dynamic Host Configuration Protocol automates the assignment of IP addresses to devices on a network.
• SNMP: Simple Network Management Protocol is used for monitoring and managing network devices.
IP Addressing
IP addressing, or Internet Protocol addressing, is a systematic method used to assign unique numerical labels to devices connected to a computer network. These numerical labels, known as IP addresses, serve two main purposes: to identify the host or network interface and to provide the location of the host in the network. IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses to accommodate the growing number of devices on the internet. Subnetting divides a larger IP network into smaller subnetworks for efficient IP address allocation. Private IP addresses are used within LANs, while public IP addresses are used for devices accessible from the internet. IP Classes (A, B, C, D, E) classify IP addresses based on their range and purpose.
Data Transmission
Bandwidth measures a communication channel’s width or capacity. Four bandwidths are voiceband, medium band, broadband, and baseband. Packet switching is a networking technology and method of data transmission where large amounts of data are broken down into smaller units called packets. These packets are then sent independently over a network and can take different paths to reach their destination. Once all packets arrive at the destination, they are reassembled to reconstruct the original data. Circuit switching is a method of communication in telecommunications networks where a dedicated communication path or circuit is established between two devices for the duration of their conversation. During this time, the entire path, including the switches and physical communication channels, is reserved exclusively for the two communicating parties. Error detection is a process employed in data communication to determine whether transmitted data contains any errors. Techniques such as checksums and CRC are used to detect and correct errors in transmitted data. Error correction, on the other hand, is a more advanced process that not only identifies but also corrects errors in transmitted data. Quality of Service (QoS) mechanisms prioritize certain types of data traffic to ensure consistent and reliable communication for applications like VoIP and video conferencing.
Network Architecture
Network architecture describes how networks are arranged and resources are shared. A network’s topology describes the physical arrangement of a network. In a bus network, devices link to a shared cable, forming a backbone. The ring network interconnects devices in a circular manner forming a ring as shown in Figure 1.












A star network involves devices directly connected to a central switch, representing the most common type in modern networks. In a tree (hierarchical) network, a central node connects to subordinate nodes, forming a tree-like structure. Figure 2 shows the star and tree network.



Mesh networks, the latest, have each node linked to two or more connecting nodes as shown in Figure 3. Networks may also adopt hybrid topologies by combining various structures to fulfill specific requirements, providing flexibility and customization.










Network Strategies
Every network has a strategy, or way of sharing information and resources. Common network strategies include client/server and peer-to-peer. In a client/server (hierarchical) network central computers coordinate and supply services to other nodes; based on specialization of nodes; widely used on the Internet; able to handle very large networks efficiently; powerful network management software available. Peer-to-peer network nodes have equal authority and act as both clients and servers; widely used to share games, movies, and music over the Internet; easy to set up and use; lacks security controls.
Internet Technologies
Internet technologies support effective communication using intranets and extranets. Intranet is a private network within an organization; uses browsers, websites, and web pages. Typical applications include electronic telephone directories, e-mail addresses, employee benefit information, internal job openings, and much more. Extranet acts like intranet except connects more than one organization; typically allows suppliers and others limited access to their networks.
Network Security
Three technologies commonly used to ensure network security are firewalls, intrusion detection systems, and virtual private networks. Firewall controls access; all communications pass through proxy server. Intrusion detection systems (IDS) work with firewalls; use sophisticated statistical techniques to recognize and disable network attacks. Virtual private network (VPN) creates secure private connection