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What Is a Computer Network?
A computer network is a system of interconnected digital devices that can communicate with each other to exchange information and share resources, data, and network services. Computer networks can be wired or wireless and public or private.
They can interconnect with other networks and contain subnetworks (subnets). These are logical subdivisions that network administrators can create to organize a computer network, control network traffic flows, improve network performance, and limit the impact of security breaches.
Key Takeaways
- Computer networks allow connected devices to share information, resources, and network services.
- Networking relies on protocols like TCP/IP to ensure different devices on the network can “speak the same language.”
- Computer network performance depends on the network’s structure, its routing efficiency, and the available bandwidth.
- Firewalls, encryption, and secure authentication can help protect networked devices from unauthorized access.
- Virtualization, cloud computing, and widespread wireless and mobile networking are changing the way computer networks are being built, deployed, and managed.
The History of Computer Networks
When computer networks were first being deployed, network administrators used cables to link multiple computers, servers, and peripheral devices together. While this ad-hoc approach to network design provided the infrastructure required for small-scale networks, it lacked scalability.
As networking technology evolved, the introduction of switches, routers, and wireless connectivity made network designs more flexible and enabled the development of larger, more complex, and more dynamic networks.
In the last decade, advancements in network virtualization and software-defined networking (SDN) have allowed organizations to create and manage virtual computer networks.
Virtual networks, which often reside in the cloud, use the same physical hardware as other networks, but function like a completely separate and independent network.
How Computer Networks Work
Computer networks rely on communication protocols to exchange information and share resources. For example, when one networked device wants to communicate with another over an IP network, the initiating device breaks the data into smaller units called packets.
Routers and switches manage the flow of packets, direct them across the network, and ensure they follow the most efficient path. DNS acts as a directory service that translates human-readable domain names into machine-readable IP addresses. This is how networked devices locate each other.
Once packets arrive at their destination, they are reassembled to form the original data. If the network’s performance is strong, this entire process happens so quickly that it feels like near-instantaneous communication.
Types of Computer Networks
Computer networks can be categorized by their topology, geographic scope, architecture, and the way they transmit data.
Network Topology
Refers to the arrangement or structure of the network.
- Bus: All network devices are connected to a single cable.
- Star: All network devices are connected to a central hub or switch.
- Ring: Network devices are connected in a circular chain.
- Mesh: Network devices are interconnected with multiple paths.
Geographic Scope
Describes the coverage of network connections.
| Network type | Definition | Technology used | Example |
|---|---|---|---|
| Local area network (LAN) | A network that connects devices in a relatively small geographical area. | Ethernet, fiber optics | Connect computers and printers in an office or home. |
| Wireless local area network (WLAN) | A wireless version of LAN that uses Wi-Fi technology. | Wi-Fi (IEEE 802.11x) | Home network connecting laptops and smartphones via Wi-Fi. |
| Metropolitan area network (MAN) | A medium-size network that connects devices in a small city or large campus. | Fiber optics, Wi-Fi, cable | Citywide network for government or public Wi-Fi. |
| Personal area network (PAN) | A very small network that connects personal devices within a few meters. | Bluetooth, Infrared (IR), USB | Connect a smartphone with wireless earbuds. |
| Wide area network (WAN) | A large network covering broad geographical areas. | Leased lines, satellite, fiber optics | Distributed enterprise networks, the Internet. |
Network’s Architecture
Refers to how the network is organized and managed.
- Client-server: A central server provides resources to client devices.
- Peer-to-peer (P2P): All devices have equal status and can share resources with each other.
Transmission Medium
Refers to the type of physical connection used.
- Wired networks: Use cables to connect devices.
- Wireless networks: Use radio waves to connect devices.
It should be noted that computer networks can also be categorized by whether they are public or private networks. A public network like the Internet is openly accessible to anyone. In contrast, a private network is restricted to a specific organization, group of users, or designated trusted devices.
Components of a Computer Network
A computer network consists of various hardware and software components that work together to facilitate communication, data sharing, and resource access. Key building blocks include end user devices, networking devices, transmission media, software components, and network security components:
Computer Network Security
Network security best practices focus on protecting the confidentiality, integrity, and availability of data in transit. This requires controlling network access with strong authentication and encrypting data so it remains private as it moves across the network.
Strategies like microsegmentation and zero-trust (ZT) can limit network damage from any single compromised device. Security awareness training and mandatory adherence to security policies can further reduce the risk of successful network attacks that use phishing and social engineering strategies.
Computer Network Security Threats
| Threat | Description | Common methods/techniques | Impact on network security | Mitigation strategies |
|---|---|---|---|---|
| Ransomware | Malware that encrypts data and demands payment to restore access | Phishing emails, malicious links, exploit kits | Data unavailability, financial loss, reputational damage | Regular backups, patch management, user training, anti-malware |
| Phishing and social engineering | Tricks users into revealing credentials or sensitive info | Emails, SMS messages, fake login pages | Credential theft, unauthorized access to systems or data | User education, email filtering, multi-factor authentication (MFA) |
| Advanced persistent threats (APTs) | Long-term, targeted attacks | Spear-phishing, zero-day exploits, malware | Intellectual property theft, ongoing espionage, data breaches | Network segmentation, intrusion detection systems (IDS), threat intelligence |
| Distributed denial-of-service (DDoS) | Makes it impossible to access a computer network | Botnets, amplified traffic attacks | Service outages, loss of revenue, reputational harm | Traffic filtering, load balancing, scalable infrastructure |
| Zero-day exploits | Attacks that take advantage of undisclosed software vulnerabilities | Unpatched OSes, applications, or devices | Fully compromises a system before a patch exists | Threat intelligence, intrusion prevention, rapid patching |
| Insider threats | Malicious or negligent actions by trusted individuals | Unauthorized data exfiltration, privilege abuse | Data leaks, sabotage, financial and reputational harm | Strict access controls, monitoring, and security audits |
Computer Network Pros and Cons
Computer networks have both pros and cons depending on their use and implementation:
Pros
- Allow connected devices to share resources such as files, printers, and Internet connections
- Networks facilitate collaboration through fast communication tools like email, instant messaging, VoIP, and video conferencing
- Can be managed centrally from either a local or remote location
- Sharing networked resources allows organizations to save money on hardware and network services
- Networks deliver SaaS apps to users over the Internet, eliminating the need for local installation and maintenance
Cons
- Vulnerable to cyberattacks
- Setting up a new network can require an investment in hardware, software, and/or cloud services
- Managing and maintaining networks can be complex and require specialized knowledge
- Shared resources can be easily compromised if access controls and the principle of least privilege (PoLP) are not implemented
- Without network segmentation, malware on one node can spread throughout the entire network
The Bottom Line
In the early days of digital computing, computer network definitions were primarily concerned with cabling mainframe computers and dumb terminals within a single location. Today, computer networks support the way people in all parts of the world communicate, share information, do business, and access entertainment.
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References
- Cybersecurity Awareness training (Learnsecurity.amazon)
