Chapter 1

Part A: Network components

Network components

Last updated November 20263 sectionsabout 8 min read

Key takeaways

A network operating system is built to manage and coordinate resources across a network; a desktop operating system is for individual, everyday use and lacks the roles, the licensing for many simultaneous connections and the reliability features of a server edition.
Server roles such as DNS, DHCP and file services are installed and enabled individually, according to what the organisation actually needs that server to do.
Working with network components follows three steps in order: classification (what type of component and its role), selection (a specific model meeting the requirement and budget) and acquisition (procurement with enough lead time).
Before deployment, check RAM, secondary storage with redundancy, a static IP address, and network speed and redundancy.
Size a host's memory by adding every role's requirement plus the host's own reserve, then leave headroom; never size to the largest single role alone.

Before a server can be racked, cabled or configured, the components it depends on must be correctly identified and specified. This chapter covers the operating system distinction that decides whether a machine can serve a network at all, the deliberate process of choosing a component rather than simply buying one, and the specific requirements every server deployment must check before going live.

Key terms

Network operating system

An operating system built to manage and coordinate resources across a network (Network Operating Systems), the software layer that turns server hardware into something a whole organisation can depend on.

Desktop operating system

A general-purpose operating system for individual, everyday use, not built for continuous multi-user server workloads: it lacks the roles, the licensing for multiple simultaneous network connections, and the reliability features a server edition provides.

Server

A computer that provides resources or services to other computers on a network, typically running a network operating system on hardware built for continuous operation.

Server roles

Specific functions a server is configured to provide, DNS, DHCP, file services and others (Network Operating Systems, under configuring the operating system), installed and enabled individually according to what the organisation actually needs that server to do.

Working with network components

Working with network components follows a deliberate process, not just plugging things in and hoping they work; skipping a step here is what produces the mismatched, poorly performing or unsupportable networks a technician is later called in to fix.

Classification

Identifying what type of component is needed, a switch, a router, a server-class machine, and the role it will play, before looking at any specific product.

Selection

Choosing a specific model or specification meeting the requirement and budget: port count and speed for a switch, throughput and features for a router, processor, memory and storage for a server.

Acquisition

Procuring the chosen component through the organisation's normal purchasing process, with enough lead time built in that a delayed delivery does not derail the whole project's schedule.

Network operating requirements

Before deployment, several requirements are checked so the server is fit for the load it will actually carry, not just able to boot.

RAM

Sufficient memory for the expected number of concurrent users and the services running, sized to the roles the server hosts rather than a generic figure, since Active Directory, a database and a file server each place different demands on memory.

Secondary storage

Enough disk capacity, and appropriate redundancy (a RAID array so a single drive failure does not lose data), for the data and services the server will host, sized with headroom for growth rather than exactly to today's need.

Static IP

A server is normally given a fixed, unchanging IP address, unlike client devices which typically receive one dynamically from DHCP, so that other systems, DNS records and firewall rules referencing the server never break when a DHCP lease would otherwise renew and change it.

Network speed and redundancy

Sufficient bandwidth for the expected load, and redundant links or components (dual network cards, dual switches) so a single failure does not take the service down entirely.

Memory demand across four roles plus the hypervisor reserve

The database role alone, accented, is nearly half the total roles' demand, 16 of 34 GB, which is exactly why sizing only the largest single role and assuming the rest 'fit somehow' understates the true requirement: every role and the hypervisor's own reserve has to be added, not just the biggest one.

Sizing memory across four planned server roles
An organisation plans a single host to run four roles as virtual machines: a file server needing 8 GB of RAM, a domain controller needing 4 GB, a web server needing 6 GB, and a database server needing 16 GB, each figure taken from the vendor's own recommended specification.
Total RAM needed by the roles themselves = 8 + 4 + 6 + 16 = 34 GB.
The host's own operating system and virtualisation layer needs a reserve, planned here at 4 GB, so total demand = 34 + 4 = 38 GB.
A host specified with 64 GB of RAM leaves 64 - 38 = 26 GB of headroom above today's requirement, room for one more moderately sized role or for the existing roles to grow, which is the kind of margin the 'sufficient memory' requirement above is checking for, not the bare minimum to start.
Specifying exactly 38 GB, or worse, sizing only the largest single role (16 GB) and assuming the rest would 'fit somehow', are both the sizing mistakes this worked calculation is meant to prevent.

Self-check

(a) Distinguish a network operating system from a desktop operating system. (2 marks)

(b) Describe the three-step process of working with network components: classification, selection and acquisition. (3 marks)

(d) Explain why a server is normally given a static IP address rather than one from DHCP. (2 marks)

(e) Four planned virtual machines need 10 GB, 6 GB, 12 GB and 4 GB of RAM respectively, and the host reserves 6 GB for itself. Compute the minimum host RAM required, and state the headroom if a 48 GB host is specified. (4 marks)

Show worked answer

(a) A network operating system is built to manage and coordinate resources across a network, with server roles and licensing for many simultaneous connections. A desktop operating system is a general-purpose OS for individual, everyday use, not built for continuous multi-user server workloads.

(b) Classification: identifying what type of component is needed and the role it will play. Selection: choosing a specific model or specification meeting the requirement and budget. Acquisition: procuring the chosen component through the organisation's normal purchasing process.

(c) Sufficient RAM for expected concurrent users and services; enough secondary storage with appropriate redundancy; a static IP address; sufficient network speed and redundancy.

(d) A static IP address ensures other systems, DNS records and firewall rules referencing the server never break when a DHCP lease would otherwise renew and assign it a different address.

(e) Minimum host RAM = (10 + 6 + 12 + 4) + 6 = 32 + 6 = 38 GB. On a 48 GB host, headroom = 48 - 38 = 10 GB.

Exam tip

A server almost always uses a static IP address rather than DHCP, so that other devices and DNS records referencing it never break when a lease renews, a frequently tested specific fact. For a sizing question, always add the host's own reserve on top of the sum of the roles' requirements before comparing against the specified hardware.