client-server model | Client-server architecture guide

The basis of modern networking is the centralized process and IT framework known as the client-server model.

For more than 50 years, servers have been the machines and mechanisms for processing end-user requests and delivering specific digital resources. These requests include anything from a Google search on a smartphone to a remote employee accessing confidential company information.

In either case, a user device initiates a request to another machine, such as a network server, which receives, filters, processes, redirects, or any combination of these actions before returning the correct response.

This article takes a look at everything you need to know about the client-server model.

What is the client-server model?

The client-server model is a network architecture that describes how servers share resources and interact with network devices. For modern businesses and data centers, there are many servers that facilitate processes such as email, printing, internet connections, application hosting, etc.

The client-server model describes how network devices such as workstations, laptops, and IoT devices – called clients – send requests to network machines or software that can meet the demand, called servers.

Although servers have historically been physical appliances like rack servers, data center trends show that administrators are increasingly deploying virtual servers for a range of workloads.

Read more: Server optimization | Increased server speed and performance

What are the components of a client-server model?

All client-server infrastructures contain three main ingredients: clients, servers and network devices to connect the two segments.

Networking device
Database server
Web application server
File server
Proxy server
IoT device
Virtual machine


Businesses once relied on workstations sharing a single operating system, but today’s computing environment strives to ensure interoperability between systems, devices, applications and products. .

As network clients are increasingly heterogeneous in terms of devices and operating systems, administrators have the added responsibility of ensuring compatibility.


The hyper-focused machines providing computing resources to customers are the physical, virtual and cloud-based servers hosted in modern data centers. Servers are the central authority for several essential digital processes that businesses rely on.

Networking devices

The framework calls physical or wireless network devices such as hubs, switches, and routers to connect servers, clients, and resources.

Once the connection between clients and servers is established, administrators can configure how client devices make requests and designate servers to perform specific tasks.

Read more: Best server security tools and software for 2021

How does the client-server model work?

A functioning client-server architecture facilitates the following process:

  1. The client submits a request through a network compatible device.
  2. The network server receives and processes the request.
  3. The server provides a response to the client.

Although simple, the client-server model is widely applicable and relevant to anyone seeking to understand content delivery networks (CDNs) or the mechanisms of edge networks. As the server’s capabilities move closer to the edge of the network, the client-server process is physically closer to end users.

Designed by Sam Ingalls, © ServerWatch 2021

Examples of client-server model

Facilitation email

Communication is essential for businesses, and postal mail cannot compete with the speed and reliability of electronic mail. Hosting email communications for an organization or network by a specific server has long been the industry’s choice for controlling particular email accounts and activity.

Using protocols such as IMAP, POP3, and SMTP, administrators can establish a system that facilitates, secures, and maintains email communications.

When using their email accounts, staff members are the customers who make requests to send emails, download attachments, and store contacts on an email server.

Read more: Best VPN Services 2021

Access web content

When a web client wants to access a specific website, it enters the URL and the browser requests an IP address from the Domain Name System (DNS). The DNS server assigns the user an IP address for identification and delivery of results.

While browsing the website, a client triggered specific web content that the user can only access through an HTTP response provided by a web server.

In this case, the end user is the customer to whom the digital content is presented. The DNS server and the web server establish and facilitate the connection to a database hosting the web content.

Advantages and disadvantages of the client-server model

Centralized data access and control
Less control of some network devices
Efficient, scalable and organized system
Initial cost and implementation
Load balancing for optimal performance
Technical expertise for continuous maintenance
Redundancy and data recovery options
Servers at risk of DoS attacks
Network of interconnected devices
Customers are attack vectors when they are raped

The different types of client-server architectures

The four types of client-server frameworks are representative of how the client-server relationship has evolved with advancements in networking.

1 level: all-in-one system

All client-server configuration settings, user interface, business logic, and database logic are located on network devices in the basic client-server architecture. Often limited to smaller networks, 1-tier frameworks include presentation, business, and data access layers on the same machine.

2 levels: client and server

2-tier architectures add a server to the mix and separate the presentation layer into a user interface, where the client makes requests outside of its capabilities. Clients and servers support more business logic and database at different levels, giving administrators some control.

3-Tier: Middleware

To protect and further enrich the 2-level architecture, this framework integrates middleware between the client level (presentation layer) and the server level (database layer).

This application layer provides a third level, allowing more complex management of business logic. Examples of middleware such as web application servers provide load balancing, increased storage, and security.

N-Tier: Multi-level architecture

Working from the 3-tier architecture, N-Tier describes the subsequent use of middleware to segment traffic and network functions. While this comes with greater complexity, modern businesses require the flexibility, scalability, and security of multilevel architectures.

Read more: Power consumption of the server room

Peer-to-Peer vs Client-Server

Although the client-server framework is the most popular distributed architecture, the most common alternative mentioned is peer-to-peer (P2P) networks.

Unlike client-server architecture, which provides a centralized flow from an organization’s servers to staff, stakeholders, and customers, a peer-to-peer network is decentralized. Network devices do not align to a specific dedicated server. Instead, P2P networks include network devices (clients) called nodes that submit and process requests to each other.

Because P2P networks love blockchains operate in a distributed fashion, connectivity is essential to operations. Compared to traditional networks, nodes tend to be more heterogeneous and share less data on the network.

The client-server model is more expensive to configure and maintain, but the reliability and scalability of the centralized framework consistently outweighs the disadvantages of peer-to-peer frameworks.

The distributed architecture of choice for enterprises

With benefits such as centralized data control, workload balancing, increased security and redundancy, the client-server model is the near universal framework for SMBs to enterprise organizations.

Compared to P2P networks, it’s easy to see why the client-server model has scaled digital operations for networks to this point. As organizations grow, adopting additional levels of client-server architecture is necessary to maintain IT infrastructure and properly secure data integrity.

To serve millions of customers and stakeholders around the world, businesses need a robust distributed framework that only the client-server model provides.

Read more : How to achieve a high availability architecture