What is a Server?

A server is, fundamentally, a computer system that provides services to other computers (clients). These services can include data storage, application execution, serving web pages, sending/receiving emails, and much more. A server is a combination of hardware and software. Hardware includes the physical components of the server (processor, memory, storage, etc.), while software includes the operating system and applications that enable the server to perform its functions.

To make an important analogy, we can think of a restaurant. Customers (clients) place orders (send requests), and waiters (servers) forward these orders to the kitchen (data processing), serving the meals (services) to the customers. The server is designed to continuously meet incoming requests and therefore often has more powerful hardware and more reliable software than desktop computers.

What are the Types of Servers and What Tasks Do They Perform?

Servers can be divided into different categories according to the services they offer and the hardware/software architectures they use. Here are the most common types of servers and their tasks:

Web Server: Serves web pages and other web content (images, videos, style files, etc.) to internet browsers. Popular web servers include Apache, Nginx, and IIS (Internet Information Services).
Email Server: Manages the sending, receiving, and storing of emails. Software such as Sendmail, Postfix, and Microsoft Exchange Server can be used as email servers.
Database Server: Hosts databases and allows clients to query, add, update, and delete data. MySQL, PostgreSQL, Oracle, and Microsoft SQL Server are popular database servers.
File Server: Stores files in a central location and provides access to users on the network. Windows Server's file sharing features and software like Samba can be used as file servers.
Game Server: Hosts multiplayer online games and manages communication between players and the rules of the game. Dedicated game servers are available for Counter-Strike, Minecraft, and other online games.
Application Server: Hosts business applications and allows clients to access these applications. Java EE application servers (GlassFish, WildFly) and .NET application servers (IIS) fall into this category.
Proxy Server: Manages traffic between clients and the internet, provides security, and improves performance. Squid, Apache, and Nginx can be used as proxy servers.
DNS Server: Translates domain names into IP addresses and enables the internet to function. BIND, PowerDNS, and Microsoft DNS Server are popular DNS servers.
Backup Server: Regularly backs up data and provides the ability to restore it in case of data loss. Bacula, Amanda, and Veeam Backup & Replication can be used as backup servers.

Example: An e-commerce site uses various servers such as a web server (user interface), database server (product information, user accounts), email server (order confirmations, promotions), and application server (payment processing, inventory management).

What Should I Consider When Choosing a Server?

Server selection depends on your needs, budget, and technical expertise. Here are some important factors to consider:

Performance: The processor (CPU), memory (RAM), and storage (disk) capacity directly affect the server's performance. Determine the processing power and storage space you need in advance.
Reliability: It is important for the server to operate without interruption. Features such as backup power supplies (UPS), RAID storage, and redundant network connections increase reliability.
Scalability: It is important that the server can be easily scaled according to your future needs. Cloud servers offer the ability to dynamically increase or decrease resources.
Security: It is important to protect the server with security measures (firewall, antivirus software, vulnerability scanning).
Operating System: The choice of server operating system (Windows Server, Linux) depends on the applications you will use and your technical expertise.
Ease of Management: It is important that the server is easy to manage. Graphical interface management tools and software that offer remote access make your job easier.
Cost: Server cost includes hardware, software, licensing, and maintenance expenses. Be careful to choose a server that does not exceed your budget.
Support: The technical support services offered by the server provider are important. You need to be able to get fast and effective support when you have problems.

Example: It makes sense to choose a high-performance, reliable, and scalable cloud server for a high-traffic e-commerce site. A more affordable shared hosting package may be sufficient for a small blog.

Physical Server, Virtual Server, or Cloud Server?

Servers are also divided into different categories according to hardware and hosting methods:

Physical Server (Dedicated Server): A physical server dedicated to a single customer. It offers full control and high performance, but its cost is higher.
Virtual Server (Virtual Private Server - VPS): Virtual servers created by dividing a physical server with virtualization technology. It is more affordable than a physical server and shares resources, but a certain amount of resources is still guaranteed.
Cloud Server (Cloud Server): Virtual servers created by combining many physical servers and providing resources dynamically. It offers scalability, flexibility, and ease of use, but its cost varies according to usage.

The following table shows a comparison of these three server types:

Feature	Physical Server	Virtual Server (VPS)	Cloud Server
Resources	Entirely yours	Shared (guaranteed)	Dynamically scalable
Control	Full control	Root Access	Root Access
Cost	Highest	Medium	Pay-as-you-go
Scalability	Limited	Limited	High
Reliability	High (hardware dependent)	Medium	High

Case Study: A startup can initially host its website and application using a virtual server (VPS). With growth, it can switch to a cloud server to meet increasing traffic and resource needs.

Server Operating Systems: Windows Server or Linux?

The choice of server operating system depends on the applications you will use, your technical expertise, and your budget. Here are the most popular server operating systems and their comparisons:

Windows Server: A server operating system developed by Microsoft. It is known for its user-friendly interface, broad application support, and Active Directory integration. It is compatible with .NET-based applications and Microsoft technologies. However, the license cost is higher.
Linux: An open-source operating system. Various distributions are available (Ubuntu Server, CentOS, Debian). It is known for its reliability, performance, and flexibility. It is widely used for web servers, database servers, and application servers. It is generally free (commercial support may be required for some distributions).

The following table shows a comparison of Windows Server and Linux:

Feature	Windows Server	Linux
License	Paid	Generally free (open source)
Ease of Use	User-friendly graphical interface	Command-line oriented (GUI distributions are also available)
Application Support	.NET, ASP.NET, Microsoft SQL Server	PHP, MySQL, PostgreSQL, Python, Java
Security	Strong security features	Strong security features (fast security updates thanks to open source)
Cost	High	Low

Example: If a company has developed a .NET-based web application and uses Active Directory, it makes sense to prefer Windows Server. If it is a web development company, it can create a more cost-effective and flexible infrastructure by using Linux.

How Do I Ensure Server Security?

Server security is critical to protecting data privacy and system integrity. Here are some measures to take to ensure server security:

Use Strong Passwords: Use complex and hard-to-guess passwords for server accounts. Change passwords regularly and enforce password policies.
Configure Firewall: Configure a firewall to protect the server from unauthorized access. Close unnecessary ports and allow only permitted traffic.
Update Regularly: Regularly install updates to close security vulnerabilities in the operating system and applications. Enable automatic updates.
Use Antivirus Software: Install antivirus software to protect the server from malware and scan regularly.
Implement Access Control: Give users only the permissions they need. Manage access using role-based access control (RBAC).
Monitor Logs: Monitor server logs regularly and detect abnormal activities. You can use a SIEM (Security Information and Event Management) system to detect security events.
Encrypt Data: Encrypt sensitive data when storing and transmitting it. Encrypt web traffic using SSL/TLS certificates.
Backup Data: Back up data regularly and store backups in a safe place. It is important to be able to restore data in case of data loss.
Perform Vulnerability Scanning: Regularly scan the server for vulnerabilities and fix any weaknesses found.
Use Two-Factor Authentication (2FA): Use two-factor authentication for remote access and critical operations.

Code Example (Linux Firewall - UFW):


# Enable UFW
sudo ufw enable

# Allow SSH access (port 22)
sudo ufw allow 22

# Allow HTTP access (port 80)
sudo ufw allow 80

# Allow HTTPS access (port 443)
sudo ufw allow 443

# Allow access from a specific IP address
sudo ufw allow from 192.168.1.100

# Check UFW status
sudo ufw status

Important Note: Server security is an ongoing process. You need to keep your security measures up to date as new threats emerge.

Server Optimization and Performance Improvement Methods

The server's performance directly affects the user experience and system efficiency. Here are some methods you can apply to improve server performance:

Resource Monitoring: Regularly monitor CPU, memory, disk, and network usage. Identify bottlenecks and optimize resources.
Caching: Reduce server load by storing frequently accessed data in the cache. You can use caching tools like Varnish or Memcached for web servers.
Database Optimization: Optimize database queries, create indexes, and configure the database server correctly.
Content Compression: Reduce bandwidth usage by compressing web pages and other content. You can use compression algorithms like Gzip or Brotli.
Use a CDN (Content Delivery Network): Distribute static content (images, videos, CSS, JavaScript) using a CDN. CDN improves performance by serving content from the server closest to the users.
Use HTTP/2: HTTP/2 is a faster and more efficient protocol than HTTP/1.1. Configure your web server to support HTTP/2.
SSL/TLS Optimization: Configure SSL/TLS certificates correctly and shorten the SSL handshake time by using techniques like OCSP Stapling.
Code Optimization: Optimize application code, remove unnecessary operations, and use efficient algorithms.
Load Balancing: Balance the server load by distributing traffic across multiple servers. Load balancing provides high availability and scalability.
Optimize the Server Operating System: Configure the server operating system to disable unnecessary services and improve performance.

Code Example (Nginx Gzip Compression):


gzip on;
gzip_disable "msie6";

gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss image/svg+xml;

Real-Life Example: A news website significantly increased its page loading speed by distributing its images and videos using a CDN. It also reduced server load by optimizing database queries and using caching.