Networking 101

IT Networking 101: Understanding the Fundamentals of Computer Networks

Computer networks are essential to modern businesses, allowing people to communicate and share information across different locations, and even across the world. A computer network is a collection of interconnected devices and systems that communicate with each other, exchanging data and resources. The network can be small, like a home network with a few devices, or large, like a corporate network with thousands of devices. In this post, we’ll cover the fundamental concepts of computer networking that every IT professional should know.

Types of Networks

Computer networks can be classified based on their size, geographical scope, and ownership. The most common types of networks are:

Personal Area Network (PAN)

A personal area network (PAN) is a network of devices that are located within a person’s reach, typically within 10 meters. Examples of devices that can be part of a PAN include smartphones, laptops, and smartwatches.

Local Area Network (LAN)

A local area network (LAN) is a network of devices located within a small geographical area, such as a building, a campus, or a group of buildings. LANs are commonly used in businesses, schools, and other organizations to connect computers, printers, and other devices.

Metropolitan Area Network (MAN)

A metropolitan area network (MAN) is a network that covers a larger geographical area than a LAN but is smaller than a wide area network (WAN). A MAN typically covers a city or a group of cities and connects LANs and other networks in the area.

Wide Area Network (WAN)

A wide area network (WAN) is a network that covers a large geographical area, such as a country, a continent, or even the whole world. WANs connect multiple LANs and MANs across different locations, enabling users to communicate and share information over long distances.

Wireless Networks

Wireless networks use radio waves to transmit data between devices, without the need for physical cables. Wi-Fi networks are a common example of wireless networks, used in homes, offices, and public places to connect devices to the internet.

Internet

The internet is a global network of networks that connects millions of devices across the world. The internet enables people to communicate, access information, and use various online services and applications.

Network Topology

Network topology refers to the physical or logical layout of a computer network. There are different types of network topology, each with its own advantages and disadvantages. Here are some of the most common types of network topology:

Bus topology: In a bus topology, all devices are connected to a single cable or backbone. Each device communicates directly with the cable and all the signals transmitted on the cable can be seen by all devices. This type of topology is relatively simple and inexpensive to implement, but it can be difficult to troubleshoot and is not suitable for large networks.
Star topology: In a star topology, all devices are connected to a central hub or switch. Each device communicates with the hub or switch, which then relays the signals to the appropriate device. This type of topology is easy to manage, and if one device fails, it does not affect the rest of the network. However, it can be expensive to implement and requires more cabling than a bus topology.
Ring topology: In a ring topology, all devices are connected in a closed loop, with each device connected to the two devices on either side of it. Each device in the ring acts as a repeater, amplifying and passing the signal along to the next device. This type of topology can provide high-speed connectivity and is relatively fault-tolerant, but it can be difficult to expand and is not suitable for large networks.
Mesh topology: In a mesh topology, each device is connected to every other device in the network. This type of topology provides high redundancy and fault tolerance, as there are multiple paths for data to travel. However, it can be expensive to implement and difficult to manage, particularly for large networks.
Hybrid topology: A hybrid topology is a combination of two or more types of topology. For example, a network might have a star topology at the core and a bus or ring topology at the edge. This type of topology provides flexibility and can be customized to suit the needs of the organization.

The choice of network topology depends on a variety of factors, such as the size of the network, the types of devices on the network, and the organization’s budget and requirements.

Networking Protocols

In the context of computer networks, a protocol is a set of rules or standards that define how data is transmitted, received, and processed over the network. Protocols are used to ensure that different devices and applications can communicate with each other and exchange information in a consistent and predictable way.

Here are some common networking protocols:

Transmission Control Protocol/Internet Protocol (TCP/IP): TCP/IP is a set of protocols that is used to connect devices to the Internet and enable communication between them. It is the most commonly used protocol for transmitting data over the Internet.
Hypertext Transfer Protocol (HTTP): HTTP is a protocol that is used to transfer data over the World Wide Web. It is the foundation of data communication for the World Wide Web and is used for requesting and transmitting web pages, images, and other content.
File Transfer Protocol (FTP): FTP is a protocol that is used to transfer files over the Internet. It is commonly used for downloading software updates and uploading website files to a web server.
Simple Mail Transfer Protocol (SMTP): SMTP is a protocol that is used to send and receive email over the Internet. It is the most commonly used email protocol for sending and receiving messages.
Domain Name System (DNS): DNS is a protocol that is used to translate domain names into IP addresses. It allows users to access websites using easy-to-remember domain names, rather than having to remember a series of numbers.
Dynamic Host Configuration Protocol (DHCP): DHCP is a protocol that is used to automatically assign IP addresses to devices on a network. It simplifies the process of setting up a network by eliminating the need to manually assign IP addresses.
Secure Sockets Layer (SSL) / Transport Layer Security (TLS): SSL/TLS are protocols used to provide secure communication over the Internet. They encrypt data transmitted between devices, providing confidentiality and integrity of data in transit.

These are just a few of the many networking protocols that exist. Different protocols are used for different purposes and applications, and each protocol has its own specific set of rules and requirements for transmitting and receiving data.

Security protocols

Security protocols are sets of rules and procedures used to secure communication over computer networks. These protocols ensure the confidentiality, integrity, and availability of information, and help prevent unauthorized access, interception, or modification of data in transit.

Here are some common security protocols used in computer networks:

Transport Layer Security (TLS) / Secure Sockets Layer (SSL): TLS and SSL are cryptographic protocols used to secure communication over the internet. They encrypt data in transit, ensuring that it can only be read by the intended recipient. TLS is used to secure HTTPS connections and is the successor to SSL.
Virtual Private Network (VPN): VPNs create a secure, encrypted connection between two networks over the internet. They are commonly used to provide remote access to corporate networks, and to secure communication between multiple offices.
IPsec: IPsec is a protocol suite used to secure communication over IP networks. It provides confidentiality, integrity, and authentication, and is commonly used in VPNs.
Secure Shell (SSH): SSH is a protocol used to secure remote access to computers and servers. It provides strong encryption and authentication, and is commonly used by system administrators to manage remote servers.
WPA / WPA2: Wi-Fi Protected Access (WPA) and WPA2 are security protocols used to secure wireless networks. They provide encryption and authentication, and are designed to prevent unauthorized access to wireless networks.
DNS Security Extensions (DNSSEC): DNSSEC is a protocol used to secure the Domain Name System (DNS). It provides authentication and integrity, and is designed to prevent DNS spoofing and cache poisoning attacks.
Kerberos: Kerberos is a protocol used for authentication in computer networks. It provides strong authentication and can be used in single sign-on (SSO) systems.

These are just a few examples of the many security protocols used in computer networks. Each protocol has its own strengths and weaknesses, and the choice of which protocol to use depends on the specific needs and requirements of the network.

Network devices

In a computer network, devices are hardware components that are used to connect, communicate, and transfer data between devices on the network. Here are some common network devices:

Router: A router is a device that is used to connect different networks and forward data between them. It determines the best path for data to travel and can filter and block unwanted traffic.
Switch: A switch is a device that is used to connect devices on a local area network (LAN). It forwards data between devices on the same network based on their physical addresses.
Hub: A hub is a device that is used to connect multiple devices on a network. It receives data from one device and broadcasts it to all other devices connected to it.
Modem: A modem is a device that is used to connect a computer or network to the Internet over a telephone or cable line. It converts digital signals from a computer into analog signals that can be transmitted over the phone or cable line, and vice versa.
Firewall: A firewall is a device that is used to protect a network from unauthorized access and attacks. It can block incoming and outgoing traffic based on predefined rules and configurations.
Network Interface Card (NIC): A NIC is a device that is installed on a computer to connect it to a network. It provides the physical connection between the computer and the network, and can be wired or wireless.
Access Point (AP): An AP is a device that is used to extend the coverage of a wireless network. It allows wireless devices to connect to the network, and can be used to create a wireless network where there is none.
Repeater: A repeater is a device that is used to boost the signal of a wireless network. It receives a weak signal from a device and retransmits it at a higher power to extend the range of the network.

These are just a few of the many network devices that exist. Different devices are used for different purposes and applications, and each device has its own specific set of features and capabilities.

Classless Inter-Domain Routing (CIDR)

CIDR stands for “Classless Inter-Domain Routing”, which is a system used for assigning and managing IP addresses in computer networks. It is an alternative to the traditional subnetting method, which was based on a system of fixed network classes (Class A, Class B, and Class C) that limited the number of available IP addresses.

CIDR allows for more flexible and efficient use of IP addresses by allowing the creation of subnets of varying sizes, without being constrained by the traditional class-based network structure. With CIDR, IP addresses are represented as a network address and a subnet mask, which allows for more precise control over the allocation and routing of IP addresses.

The subnet mask determines the number of bits in the network portion of the IP address, and the remaining bits are used for the host portion. For example, in a CIDR notation, an IP address might be represented as 192.168.1.0/24, where the “/24” indicates that the first 24 bits of the IP address are reserved for the network portion, and the remaining 8 bits are used for the host portion.

CIDR has several benefits, including:

Efficient use of IP addresses: CIDR allows for more efficient use of IP addresses, as it allows for the creation of subnets of varying sizes, which can reduce the number of unused or wasted IP addresses.
Flexible network design: CIDR allows for more flexible network design, as it is not limited by the traditional class-based network structure.
Simplified network management: CIDR can simplify network management by allowing for easier allocation and routing of IP addresses, which can reduce the complexity of network configurations.

Overall, CIDR is an important system for managing IP addresses in computer networks, and has played a significant role in improving the efficiency and flexibility of network design and management.

IP Addressing

IP addressing is a critical aspect of computer networking that enables devices to communicate with each other over a network. An IP address is a numerical identifier assigned to each device on a network. The IP address is used to identify and communicate with devices on the network.

An IP address is a 32-bit number that is usually represented in decimal format with four decimal numbers separated by periods. For example, an IP address might look like 192.168.1.1. IP addresses are divided into two parts: the network address and the host address. The network address identifies the network that the device is connected to, while the host address identifies the specific device on that network.

There are two versions of IP addresses in use today: IPv4 and IPv6. IPv4 is the older version and uses a 32-bit address space, which provides about 4.3 billion possible addresses. IPv6 is the newer version and uses a 128-bit address space, which provides an almost unlimited number of possible addresses.

IP addresses can be assigned to devices in several ways. They can be assigned manually, where a network administrator manually enters the IP address for each device. They can also be assigned automatically, using protocols such as Dynamic Host Configuration Protocol (DHCP), which automatically assigns IP addresses to devices when they connect to the network.

IP addresses can be either public or private. Public IP addresses are assigned by Internet Service Providers (ISPs) and are used to identify devices on the Internet. Private IP addresses are used for devices on a private network, such as a home or office network. Private IP addresses are not accessible from the Internet and are used to identify devices within a private network.

Feature	IPv4	IPv6
Address length	32 bits	128 bits
Address notation	Decimal (dotted-decimal) notation	Hexadecimal notation (8 blocks of 4 hex digits)
Address space	Limited (about 4.3 billion addresses)	Very large (over 340 undecillion addresses)
Address types	Public, private, and loopback addresses	Global unicast, unique local, and link-local
Address configuration	Manual configuration or DHCP	Manual configuration, DHCPv6, or SLAAC
Header length	Fixed length header (20 bytes)	Variable length header (40 bytes or more)
Security	Limited security features	Built-in IPSec support
Fragmentation	Host-dependent fragmentation	Router-based fragmentation
Quality of Service (QoS)	DiffServ for traffic prioritization	Flow Label field for QoS
Backward compatibility	IPv4 is backward-compatible with IPv6	IPv6 is not backward-compatible with IPv4

IPv4 vs IPv6

Dynamic Host Configuration Protocol, (DHCP)

DHCP stands for Dynamic Host Configuration Protocol, and it is a network protocol used to automatically assign IP addresses and other network configuration settings to devices on a network. DHCP makes it easier to manage large networks and reduces the likelihood of IP address conflicts.

DHCP operates using a client-server model. When a device (such as a computer or mobile device) connects to a network, it sends a DHCP request to a DHCP server. The server then assigns an available IP address to the device, along with other network configuration settings like the subnet mask, default gateway, and DNS server addresses.

DHCP servers can be configured to assign IP addresses dynamically or statically. Dynamic assignment means that IP addresses are assigned on a temporary basis, and are released back to the pool of available addresses when the device disconnects from the network. Static assignment means that IP addresses are assigned on a permanent basis, and are reserved for specific devices.

DHCP provides several benefits, including:

Automatic IP address assignment: DHCP eliminates the need to manually configure IP addresses on every device on the network, saving time and reducing the likelihood of configuration errors.
Centralized network management: DHCP servers can be used to centrally manage network configuration settings, making it easier to make changes and ensuring that settings are consistent across the network.
IP address conservation: DHCP servers can be configured to reuse IP addresses that have been released back to the pool, reducing the need for additional IP addresses.
Improved security: DHCP can be used to enforce security policies, such as preventing unauthorized devices from connecting to the network.

DHCP is a widely used protocol and is supported by most operating systems and network devices. It is an important component of modern network infrastructure and plays a critical role in simplifying network management and improving network efficiency.

Domain Name System (DNS)

DNS stands for Domain Name System, and it is a hierarchical and distributed naming system used to translate human-readable domain names, such as “google.com”, into IP addresses that can be understood by computer networks. It is essentially a system of servers and databases that work together to provide a central directory of domain names and IP addresses.

DNS operates using a client-server model. When a user types a domain name into a web browser, the browser sends a request to a DNS resolver (a client) to look up the IP address associated with that domain name. The resolver then queries a series of DNS servers (starting with the local DNS server, and then moving up the hierarchy to authoritative DNS servers) until it finds the IP address associated with the domain name.

The DNS system is structured into a hierarchy of domains, with the root domain (represented by the period “.”) at the top, followed by top-level domains (TLDs) like .com, .org, and .net. Below the TLDs are second-level domains (SLDs), such as “google.com”, and then subdomains, such as “mail.google.com”.

The DNS system provides several benefits, including:

Human-readable domain names: DNS allows users to type in domain names that are easy to remember and understand, rather than having to remember long strings of numbers.
Load balancing and fault tolerance: DNS can be used to distribute network traffic across multiple servers or data centers, improving performance and ensuring that the network remains available even if one server goes down.
Caching: DNS resolvers can cache DNS queries to improve performance and reduce the load on the DNS system.
Security: DNS can be used to enforce security policies, such as blocking access to known malicious domains or preventing access to unauthorized network resources.

Overall, DNS is a critical component of the internet and computer networks, and plays an important role in ensuring that users can access the resources they need and that network traffic is efficiently routed across the internet.

Network performance

Network performance refers to the speed, reliability, and efficiency of a computer network. A well-performing network is one that is fast, responsive, and able to handle a high volume of traffic without experiencing bottlenecks or slowdowns.

There are several factors that can affect network performance, including:

Bandwidth: Bandwidth refers to the amount of data that can be transmitted over a network at any given time. A network with higher bandwidth is able to transmit more data, which can lead to faster and more efficient performance.
Latency: Latency is the time it takes for data to travel between two devices on a network. High latency can lead to delays and slowdowns in data transmission.
Packet loss: Packet loss occurs when data packets are lost or dropped during transmission. High packet loss rates can slow down network performance and result in the need for retransmissions.
Network congestion: Network congestion occurs when there is too much traffic on a network, which can slow down the transmission of data.
Network topology: The topology of a network can affect its performance. A well-designed network topology can reduce latency and packet loss, which can lead to better performance.

To improve network performance, there are several strategies that can be used, including:

Network optimization: Optimizing a network involves identifying and resolving issues that may be causing bottlenecks or slowdowns in performance. This can include upgrading hardware, adjusting configurations, and optimizing routing and switching protocols.
Load balancing: Load balancing involves distributing network traffic across multiple devices or paths to avoid congestion and improve performance.
Quality of Service (QoS): QoS is a set of protocols and techniques that can be used to prioritize and manage network traffic to ensure that high-priority traffic is given preferential treatment.
Network monitoring: Network monitoring involves the use of tools and techniques to track and analyze network performance. This can help identify issues and optimize network performance in real-time.

Overall, network performance is critical to ensuring that computer networks operate efficiently and effectively. By identifying and addressing performance issues, network administrators can improve network performance and ensure that their networks are able to meet the needs of their users.

Conclusion

Computer networks are essential to modern businesses, enabling people to communicate and share information across different locations and devices. Understanding the fundamentals of computer networking is essential for IT professionals, as it enables them to design, implement, and maintain networks that meet the needs of their organization. In this post, we covered the different types of networks, network topologies, network protocols, and network devices that are commonly used in computer networks. By mastering these concepts, IT professionals can build robust, secure, and efficient computer networks that enable their organization to achieve its goals.