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 choose from several types of slots and sockets, so you have to make sure that the motherboard supports the specific slot or socket style used by the CPU. Some server motherboards have two or more slots or sockets to hold two or more CPUs.
What’s more, processor cores utilize a technology called hyperthreading, which effectively lets each processor core juggle two threads at once. (In general terms, a thread is a sequence of instructions that performs a single task.) Because each core can handle two simultaneous threads, a processor with four cores can handle eight concurrent threads.
Many server motherboards can support two separate processors, which doubles the potential workload of the server. For example, if the server has two 14-core processors, the server has a total of 28 cores available for its workload. Because of hyperthreading, each of these 28 cores can handle 2 threads, so the server can handle 56 concurrent threads.
Memory
