Networking is 23% of A+ Core 1. Most questions stay at support-technician depth: identify the service, device, connection, or setting that solves the stated need without drifting into router-engineering detail.
Fast rule: Separate the job before choosing the technology. A port identifies a service endpoint, DHCP provides client configuration, DNS resolves names, a router moves traffic between networks, an access point provides wireless access, and a modem or other WAN device connects the local network to an outside service.
1. Networking decision map
| Need | Think first | Clue |
|---|---|---|
| Reach a known service | Protocol and port | Web, email, file transfer, remote administration, name resolution |
| Give clients network settings | DHCP | Address, mask/prefix, gateway, DNS settings |
| Translate a host name | DNS | Name works/fails separately from IP reachability |
| Connect wireless clients | Access point / wireless router | SSID, band, channel, encryption, signal |
| Move traffic between networks | Router | Default gateway or separate IP networks |
| Test physical network media | Cable/network tool | Pinout, continuity, tone, cable location |
2. Connect common ports to the service, not the number alone
At A+ depth, the useful memory is service → secure or insecure option → common port.
Examples worth keeping fresh include:
- HTTP / HTTPS for web access
- SSH for secure command-line remote administration
- RDP for Windows remote desktop
- DNS for name resolution
- DHCP for automatic client configuration
- SMTP, POP3, and IMAP for email transport or retrieval
- SMB for Windows-oriented file and printer sharing
- FTP, SFTP, and related file-transfer choices
- LDAP/LDAPS for directory access
- SNMP for network monitoring
- NTP for time synchronization
Use the Ports and Protocols Reference for the complete list rather than turning this page into a number chart.
A port can suggest a service, but the scenario still matters. If the requirement says secure remote shell, SSH is stronger than selecting Telnet because both are remote command tools.
3. Choose wireless technology from range, compatibility, and interference
Core 1 includes Wi-Fi bands, standards, channels, and short-range wireless technologies.
Wi-Fi bands
- 2.4 GHz: longer reach and better obstacle penetration, but fewer clean channel choices and more interference.
- 5 GHz: more channel capacity and commonly less congestion, but shorter effective reach through obstacles.
- 6 GHz: additional spectrum for supported Wi-Fi devices, with client compatibility and range still mattering.
A higher frequency is not automatically the better answer. A distant room with several walls may favor reach over peak throughput.
Channels and interference
On 2.4 GHz Wi-Fi in common U.S. deployments, channels 1, 6, and 11 are the familiar non-overlapping 20 MHz choices.
If users have strong signal but poor throughput in a crowded area, channel contention or interference can matter more than adding transmit power.
Short-range wireless
- Bluetooth: peripheral and short-range device connectivity
- NFC: very short-range exchange and tap-style interactions
- RFID: identification/tracking use cases
- Cellular: wide-area mobile connectivity
Choose the technology from the required range and function, not because all four are wireless.
4. Separate addressing, DNS, DHCP, VPN, and host roles
DHCP
Dynamic Host Configuration Protocol (DHCP) provides client network configuration automatically.
A Windows client that falls back to a 169.254.x.x address did not receive its expected IPv4 configuration. That points toward the local link or DHCP path before DNS.
DNS
Domain Name System (DNS) translates names and related records.
If a user can reach a server by IP address but not by host name, DNS becomes a strong clue because basic IP communication already works.
Default gateway
The default gateway is where a client sends traffic destined for another network. A client can have a valid local IP address and still fail to reach remote networks if its gateway is wrong.
VPN
A Virtual Private Network (VPN) protects communication across another network and can provide remote or site connectivity. It does not replace user authorization or endpoint security.
Common host/service roles
Know the job of common systems such as:
- File server
- Print server
- Web server
- Mail server
- Database server
- Authentication/directory server
- DHCP server
- DNS server
- Proxy server
- Network-attached storage
- Embedded/Internet of Things devices
A server role describes what service the system provides. The physical machine may host more than one role.
5. Match infrastructure devices to the traffic decision
| Device | Main job | Scenario clue |
|---|---|---|
| Switch | Connect devices on a local Ethernet network | More wired LAN ports or local frame switching |
| Router | Move traffic between IP networks | Default gateway or path to another network |
| Access point | Provide Wi-Fi access to a network | Add or improve wireless coverage |
| Firewall | Allow or block traffic according to policy | Restrict unwanted communication |
| Modem/ONT | Terminate the provider access technology | Cable, DSL, fiber, or other WAN service handoff |
| PoE switch/injector | Deliver Ethernet plus supported power | AP, phone, camera, or other powered Ethernet device |
Many SOHO devices combine router, switch, access point, firewall, and DHCP functions in one box. The exam can still ask which function is relevant to the scenario.
6. Build a SOHO network from the outside in
A basic small-office/home-office path is:
provider connection → modem/ONT or provider handoff → router/firewall → switch or wireless access → client
Useful setup decisions include:
- Change default administrative credentials.
- Install supported firmware updates.
- Configure the internet/WAN settings required by the provider.
- Use an appropriate local addressing and DHCP range.
- Configure strong supported Wi-Fi security.
- Choose suitable bands/channels for the environment.
- Separate guest access when untrusted devices should not reach internal resources.
- Limit unnecessary remote management and exposed services.
If a user needs better Wi-Fi coverage in a distant part of the building, adding or repositioning an access point is a different solution from replacing the ISP connection.
7. Compare internet links and network types by purpose
Internet access may use technologies such as:
- Fiber
- Cable
- DSL
- Cellular
- Satellite
- Fixed wireless
The best choice depends on availability, throughput, latency, reliability, mobility, and cost.
Network-type terms also describe scope or purpose:
- LAN: Local Area Network
- WLAN: wireless LAN
- WAN: Wide Area Network
- PAN: Personal Area Network
- MAN: Metropolitan Area Network
- SAN: Storage Area Network
Do not confuse the connection technology with the network's logical scope. Fiber can be used inside a LAN or as an internet/WAN service.
8. Choose the network tool from the evidence you need
| Tool | Best use |
|---|---|
| Cable tester | Verify continuity, mapping, and common wiring faults |
| Toner probe | Identify or trace a cable |
| Crimper | Attach supported modular connectors |
| Loopback plug | Test supported interface transmit/receive behavior |
| Wi-Fi analyzer | View nearby Wi-Fi networks, channels, and signal information |
| Network tap | Provide a copy of network traffic for analysis |
Choose the tool that answers the physical or wireless question. A toner can help find a cable, but it does not prove that DHCP is working.
9. Scenario comparisons
User reaches websites by IP address but not by name
Think DNS. The client already demonstrated basic IP connectivity.
Laptop has a 169.254 address
Think local link and DHCP before DNS.
Office has dead Wi-Fi coverage in one wing
Think access-point placement/coverage before replacing the modem.
Company wants untrusted visitors online without broad access to internal devices
Use guest wireless/network separation with appropriate policy rather than sharing the internal wireless access unchanged.
Technician needs to identify which wall jack maps to a cable in the closet
Use a toner probe.
A support question says "secure command-line remote administration"
Think SSH, not a generic remote-access protocol simply because it is familiar.
10. Common exam traps
- Changing DNS when the client never received valid IP configuration.
- Treating the router, modem, switch, and access point as interchangeable names.
- Assuming the highest Wi-Fi frequency is always the best answer.
- Choosing a port number without first identifying the service.
- Treating a VPN as proof that the user should receive unrestricted internal access.
- Replacing the ISP connection for a local wireless-coverage problem.
- Treating a Wi-Fi analyzer as a cable-continuity tester.
- Assuming a combined SOHO router means the individual network functions no longer matter.
- Confusing PAN, LAN, WAN, and internet-access technologies.
- Ignoring client compatibility when recommending a newer wireless band or standard.
11. Rapid review grid
| Clue | Think first |
|---|---|
| Automatic client network settings | DHCP |
| Name to address | DNS |
| Traffic to another IP network | Router/default gateway |
| Wireless LAN access | Access point |
| Filter communication | Firewall |
| 169.254.x.x | DHCP/local link |
| Trace a cable | Toner probe |
| Inspect nearby Wi-Fi channels | Wi-Fi analyzer |