Rolodex. And then there were the nonbook versions: When you needed to find the Sam Goody store at a shopping mall (for example), you looked for the mall directory — usually, a lighted sign showing what was where.
Networks have directories, too, providing information about the resources that are available on the network: users, computers, printers, shared folders, and files. Directories are essential parts of any server operating system.
The most popular modern directory service is called Active Directory. Active Directory is a standard component of all Windows operating systems, and because it’s so popular, most other operating systems support it as well. Active Directory is a database that organizes information about a network and all its computers and users. It’s simple enough to use for networks with just a few computers and users, but powerful enough to work with large networks containing tens of thousands of computers and users. Figure 5-1 shows the Active Directory Users and Computers tool, which manages Active Directory user and computer accounts on Windows Server 2019.
FIGURE 5-1: Managing Active Directory Users and Computers.
Security services
All server operating systems must provide some measure of security to protect the network from unauthorized access. Hacking seems to be the national pastime these days. With most computer networks connected to the Internet, anyone anywhere in the world can — and probably will — try to break into your network.
The most basic type of security is handled through user accounts, which grant individual users the right to access the network resources and govern which resources the user can access. User accounts are secured by passwords; therefore, good password policy is a cornerstone of any security system. Most server operating systems give you some standard tools for maintaining network security:
Establish password policies. For example, you can mandate that passwords have a minimum length and include a mix of letters and numerals.
Set passwords to expire after a certain number of days. Network users must change their passwords frequently.
Encrypt network data. A data-encryption capability scrambles data before it’s sent over the network or saved on disk, making unauthorized use a lot more difficult. Good encryption is the key to setting up a virtual private network (VPN), which enables network users to securely access a network from a remote location by using an Internet connection.
Manage digital certificates. Digital certificates are used to ensure that users are who they say they are and files are what they claim to be.
The overwhelming majority of business networks rely on server versions of Windows, known as Windows Server. Microsoft periodically releases updated versions of Windows Server, so Windows Server is frequently improved, and older versions are occasionally rendered obsolete. Currently, the most commonly used versions are Windows Server 2012 Release 2, Windows Server 2016, and the latest-and-greatest version, known as Windows Server 2019.
But Windows Server is not the only server operating system at your disposal. Many servers — especially those whose primary responsibility is to host websites — use Linux instead of Windows Server. Apple also makes an excellent server operating system, known as OS X Server.
What’s Important in a Server
The following sections point out some general things to keep in mind when selecting the equipment that a server should run on.
Scalability
Scalability is the ability to increase the size and capacity of the server computer without unreasonable hassle. Purchasing a server computer that just meets your current needs is a major mistake because (rest assured) your needs will double within a year. If at all possible, equip your servers with far more disk space, RAM, and processor power than you currently need.
Reliability
The old adage “you get what you pay for” applies especially well to server computers. Why spend $5,000 on a server computer when you can buy one with seemingly similar specifications at a discount electronics store for a mere $1,000? The main reason: reliability. When a client computer fails, only the person who uses that computer is affected. When a server fails, however, everyone on the network is affected. The less-expensive computer is probably made of inferior components that are more likely to fail, and does not have redundant components built in. (For example, many server computers have two power supplies, two CPUs, two or more network interfaces, and other redundant components.)
Availability
This concept is closely related to reliability. When a server computer fails, how long does it take to correct the problem and get the server up and running again? Server computers are designed so their components can be easily diagnosed and replaced, which minimizes the downtime that results when a component fails. In some servers, components are hot swappable (certain components can be replaced without shutting down the server). Some servers are fault-tolerant so that they can continue to operate even if a major component fails.
Service and support
Service and support are often overlooked factors when picking computers. If a component in a server computer fails, do you have someone on site qualified to repair the broken computer? If not, you should get an on-site maintenance contract for the computer.
Components of a Server Computer
The hardware components that make up a typical server computer are similar to the components used in less-expensive client computers. However, server computers are usually built from higher-grade components than client computers for the reasons given in the preceding section. The following paragraphs describe the typical components of a server computer:
Motherboard
A motherboard is the computer’s main electronic circuit board to which all the other components of your computer are connected. More than any other component, the motherboard is the computer. All other components attach to the motherboard.
The major components on the motherboard include the processor (CPU); supporting circuitry (the chipset); memory (RAM); expansion slots; a hard drive controller; USB ports for devices such as keyboards and mice; a graphics adapter; and one or more network interfaces.
Processor
The CPU is the brain of the computer. Although the processor isn’t the only component that affects overall system performance, it’s the one that most people think of first when deciding what type of server to purchase. At the time of this writing, most servers used one of several variations of Intel’s Xeon processor. These processors are designed specifically for server computers rather than client computers, and offer from 4 to 22 independent processor cores, depending on the model.
Each motherboard is designed to support a particular type of processor. CPUs come in two basic mounting styles: slot or socket. However, you can