CompTIA A+ 220-1201 - Next Seven Videos

2.4 GHz Non-overlapping Channels

Channels 1, 6, and 11.

ISM Band

Industrial, Scientific, and Medical frequencies used without a license (e.g., Wi-Fi).

Passive RFID

Tags with no battery that are powered by the scanner's signal.

Active RFID

Tags with their own power source that work at longer distances.

NFC (Near Field Communication)

An extension of RFID that allows for two-way (bidirectional) communication.

Syslog

The protocol used by devices to send log data to a server.

SIEM

A server that receives, stores, and analyzes log data from various devices.

Proxy Server

A device sitting between clients and servers used for security, filtering, and caching.

Load Balancer

A device sitting between clients and servers used for performance, uptime, and failover.

SCADA

Supervisory Control and Data Acquisition; controls physical industrial equipment.

IoT (Internet of Things)

Smart devices with often weak built-in security that require network segmentation.

AAA

Authentication, Authorization, and Accounting.

DNS A Record

Maps a hostname to an IPv4 address.

DNS AAAA Record

Maps a hostname to an IPv6 address.

DNS CNAME Record

Canonical Name; maps one name to another (an alias).

DNS MX Record

Mail Exchanger; identifies the email server for a domain.

DNS TXT Record

Text record; used to store human-readable or machine-readable (SPF/DKIM) data.

SPF (Sender Policy Framework)

A DNS TXT record listing approved senders for a domain.

DKIM (DomainKeys Identified Mail)

Adds a digital signature to email messages to verify they weren't altered.

DMARC

Policy that defines what to do if SPF or DKIM checks fail.

dig

DNS lookup tool used primarily on Linux and macOS.

nslookup

DNS lookup tool used primarily on Windows.

TTL (Time to Live)

How long to keep a piece of data cached before checking for an update.

DORA Process

Discover, Offer, Request, Acknowledge (DHCP sequence).

DHCP Discover/Request Source IP

0.0.0.0 (used because the client does not yet have an IP).

DHCP Broadcast Address

255.255.255.255.

DHCP Reservation

Linking a specific MAC address to a specific IP address so it never changes.

DHCP Ports

Server listens on UDP 67; Client communicates on UDP 68.

VLAN (Virtual Local Area Network)

A way to create multiple broadcast domains on a single physical switch.

Inter-VLAN Communication

Requires a router or a Layer 3 switch.

Client-to-Site VPN

A remote user connecting individually to a corporate network.

Site-to-Site VPN

Connecting two entire office locations together over the internet.

VPN Concentrator

A device (often a firewall) that handles encryption and decryption for VPN tunnels.