12. CompTIA A+ | Services Provided by Networked Hosts

Server

A computer that provides a service or resource to other devices (clients) on the network.

DNS server

Translates domain names (like google.com) into IP addresses.

DHCP server

Automatically assigns IP addresses and network settings (subnet mask, gateway, DNS) to devices.

File share server

Stores files in a central location so users can access and share them over the network.

Print server

Manages print jobs and shared printers for multiple users on the network.

Mail server

Sends, receives, and stores email for users (uses SMTP, POP3, IMAP).

Web server

Hosts websites and delivers web pages to browsers (uses HTTP and HTTPS).

Database server

Stores and manages databases that applications and users can query (often using SQL).

Syslog server

Collects and stores log messages from many network devices in one central place.

NTP server

Network Time Protocol. Keeps the time synchronized on all devices across the network.

Why does accurate time (NTP) matter on a network?

Logs need correct timestamps, and authentication systems can fail if device clocks don’t match.

AAA

Authentication, Authorization, and Accounting.

Authentication

Proving who you are (username and password, biometrics, MFA).

Authorization

Determining what you’re allowed to access after you log in.

Accounting

Tracking what users do, like logins, time connected, and resources used.

AAA server examples

RADIUS and TACACS+ are common protocols used by AAA servers.

Spam gateway

Filters incoming email to block spam, phishing, and malicious messages before they reach users.

UTM (Unified Threat Management)

An all-in-one security appliance that combines firewall, antivirus, intrusion prevention, content filtering, and spam filtering.

Load balancer

Spreads incoming traffic across multiple servers so no single server gets overloaded.

Proxy server

Sits between users and the internet, making requests on their behalf. Can filter content, cache pages, and hide internal IP addresses.

SCADA

Supervisory Control and Data Acquisition. Systems that monitor and control industrial equipment like power plants, water treatment, and factories.

Legacy/embedded system

An older or specialized system that can’t easily be updated, like SCADA. Often isolated from the rest of the network for security.

IoT (Internet of Things) devices

Everyday devices connected to the network: smart thermostats, cameras, doorbells, light bulbs, and speakers.

Why should IoT devices be on a separate network or VLAN?

They’re often poorly secured and rarely updated, so isolating them protects the rest of the network.

A company’s website crashes whenever traffic spikes, what devices spreads traffic across multiple servers?

Load balancer

A small business wants one device that handles firewall, antivirus, and content filtering. What should they get?

UTM appliance

Users are getting a lot of phishing emails. What appliance can help filter them?

Spam gateway

A tech needs to review logs from all the switches and routers in one place. What server is used?

Syslog server

Event logs on different servers show conflicting times, making troubleshooting difficult. What service fixes this?

NTP

A company wants to control and log which websites employees visit. What server could do this?

Proxy server

A user can log in to the network but can’t open the HR folder. Which part of AAA is involved?

Authorization