CompTIA Network+ (N10-009) (Concise) (Personal) (Continuously Editing)

Personal flash cards based on what I got wrong and need to study more. I frequently edit and update them to try to get only Net+ Necessary info while being concise (15-20 words max). Terms and definitions largely based on DionTraining's Udemy exams

Network Baseline

• Documented measurement of normal network performance & traffic

• Used to detect abnormalities, misconfigurations, or security incidents

CIDR

Jumbo frames

• Ethernet frames with MTU greater than 1500 bytes

• Commonly used on SANs to improve performance

Virtual Private Cloud (VPC)

• Logically isolated virtual network in a public cloud

• Where resources run with defined IP ranges and routing

NAT Gateway

• Allows private VPC resources outbound internet access

• While preventing direct inbound internet connections

Optimizing routing paths

• Selecting more efficient network routes

• To reduce latency and improve application response times

Wi-Fi PSK (Pre-Shared Key)

• Single shared wireless password used by all clients for network access

Enterprise Wi-Fi

• Uses 802.1X with RADIUS for per-user authentication

• No shared PSK

• Designed for managed corporate networks

MDF (Main Distribution Frame)

• Central location where external provider cabling enters & terminates

• Before distributing to internal network

Backdoor

• Hidden access method

• Allows unauthorized remote access

• Actions aren’t logged

• Doesn’t require normal authentication

Wiring Diagram

• Shows exact cable-to-port connections (which cable plugs into which switchport)

Physical Network Diagram

• Shows physical layout of devices and cabling

• Not detailed port-to-cable labels

Logical Network Diagram

• Shows

  • Traffic flow

  • Subnets

  • VLANs

  • Routing

  • logical relationships

• Doesn’t show physical cabling

Site Survey Report

• Wireless-focused document

• Shows

  • Coverage

  • Signal strength

  • Interference

  • Access point placement

Voice VLAN

• Separate VLAN on switch ports to prioritize VoIP traffic

• Uses QoS markings (802.1p)

• improves call quality

Data VLAN (Access VLAN)

• VLAN assigned to workstation traffic on a switch port

• Carries non-voice user data

VLAN Numbers (100, 200, etc.)

• Numeric identifiers (1–4094)

• Used to logically separate traffic

• Numbers themselves have no inherent priority

Triple-homed firewall

• Firewall with three interfaces

• Connects internal network, external internet, & DMZ

tcpdump command

• Command-line packet capture tool

• Used to:

  • Analyze network traffic

  • Inspect packets in real time

dig command

• DNS query tool

• Used to verify

  • DNS records

  • Nameservers

  • Domain-to-IP mappings

802.11a

• 5 GHz band

• Up to 54 Mbps

802.11b

• 2.4 GHz

• Up to 11 Mbps

802.11g

• 2.4 GHz

• Up to 54 Mbps

802.11n

• 2.4 GHz & 5 GHz

• Up to 600 Mbps

802.11ac

• 5GHz

• Up to 6.9 Gbps

802.11ax

• 2.4GHz &5GHz

• Up to 9.6 Gbps

VXLAN

• Encapsulation technology

• Extends Layer 2 networks over Layer 3

• Uses UDP tunneling

VXLAN Network Identifier (VNI)

• 24-bit identifier

• Used to distinguish/separate different VXLAN overlay networks

VXLAN overlay network

• Virtual Layer 2 network

• Built over Layer 3 underlay

• Uses VXLAN encapsulation

VXLAN Overlay vs Underlay

• Overlay = logical network you design

• Underlay = physical IP network carrying the traffic

Native VLAN

• VLAN assigned to untagged frames on an 802.1Q trunk

• Used for compatibility, not traffic prioritization

Packet-switched Network

• Transmits data by breaking it into packets

• Routed independently across network

• Reassembled at destination

Firewall rules / ACLs

• Ordered permit/deny rules evaluated top-down

• First rule match stops further rule evaluation

• Ends with an implicit deny

ACL rule order

• Place specific rules before general rules so they are evaluated first

Implicit deny

• All traffic not explicitly permitted is denied by default.

DENY ANY ANY

• Blocks all traffic from any source to any destination

Teredo Tunneling

• IPv6 transition technology

• Encapsulates IPv6 traffic inside IPv4

• Enables connectivity over IPv4-only networks

Twinaxial

• Short-range high-speed copper cable

• Used for:

  • Switch-to-switch links

  • SATA 3.0 connections

Link aggregation vs LACP

• Link Aggregation is the general concept

• LACP (802.3ad) is specific, automated protocol that manages this process dynamically

Routing Protocol Types (Contrast Card)

• Distance Vector: Hop count

• Link-State: Topology map

• Path-Vector: AS paths between networks

Distance Vector

• Routers share routes with neighbors

• Selects paths using hop count

• Example: RIP

Routing Convergence

• Time required for routers to agree on best paths after a topology change

Link-State Routing (e.g., OSPF)

• Routers share full topology

• Calculate shortest path

• Fast convergence

• Higher overhead

Path-Vector Routing (BGP)

• Uses AS-path info & policy to route between autonomous systems

• Prioritizes policy, not speed
  

802.11h

• Adds Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC)

• To comply with radar-avoidance regulations

Subnet Mask

• Defines network & host portions of an IP address

• Determines local subnet membership & whether traffic is routed

SIEM (Security Information and Event Management)

• Centralizes & correlates logs

• Provides real-time

  • Security alerting

  • Monitoring

  • Incident detection

  • Compliance reporting

TCP SYN Scan Nmap flag

• -sS

• Performs a half-open (SYN) scan to identify open TCP ports

UDP Scan Nmap flag

• -sU

• Scans UDP ports to identify open services (DNS, SNMP, DHCP)

Service Version Detection Nmap flag

• -sV

• Identifies service types & version numbers running on open ports

Operating System Detection Nmap flag

• -O

• Attempts to determine the operating system of the target

Virtual IP (VIP)

• Shared IP address

• Provides a single access point to services hosted by multiple servers

Virtual IP (VIP) high availability

• Enables load balancing & failover

• Directs client traffic to available servers behind the VIP

LACP

• Link Aggregation Control Protocol

• Bonds multiple physical switch ports into one logical link for speed & redundancy

LACP Purpose

Increases bandwidth & fault tolerance between network devices by aggregating links

LLDP

• Layer 2 discovery protocol

• Used by devices to advertise identity, capabilities, and neighbors

L2TP (Layer 2 Tunneling Protocol)

• Tunneling protocol used for VPNs

• Not for increasing link speed or redundancy

• Doesn’t provide encryption

LDAP

• Application-layer protocol

• Used to access and manage directory services, such as user authentication

Northbound Traffic

Network traffic exiting the datacenter to external networks through a firewall or router

Southbound Traffic

Network traffic entering the datacenter from external networks through a firewall or router.

East-West Traffic

Traffic flowing internally between systems within the datacenter, such as server-to-server communication.

Single-mode Fiber

• Fiber with a small core

• Carries one light path,

• Supporting long distances & higher bandwidth

Multimode Fiber

• Fiber with a larger core

• Carries multiple light paths

• Used for shorter distances

10GBase-FX

• 10 Gigabit Ethernet

• Over single-mode fiber

• Not compatible with copper cabling

10GBase-T

• 10-Gigabit Ethernet

• Over twisted-pair copper

• Uses Cat 6a cabling up to 100 meters

10GBase-SR

• 10-Gigabit Ethernet

• Over multimode fiber

• Uses short-range optical wavelengths

10GBase-SW

• 10-Gigabit Ethernet

• Over fiber

• Designed for SONET environments, not standard Ethernet LANs

Border Gateway Protocol Function

• Exchange routing information between autonomous systems (AS)

• Enables inter-domain routing across Internet
  

Autonomous System

• Collection of IP networks

• Under one administrative control

• Share common routing policy

Interior vs exterior routing protocols

• Interior gateway protocols route within an autonomous system

• Exterior gateway protocols route between autonomous systems

RIP (routing protocol)

• Distance-vector routing protocol using hop count

• Maximum 15 hops

• Slow convergence

• Legacy networks

• Interior gateway protocol

OSPF (routing protocol)

• Link-state routing protocol using cost metric

• Fast convergence

• Commonly used in enterprise networks

• Interior Gateway Protocols

EIGRP (routing protocol)

• Cisco-proprietary hybrid routing protocol

• Uses bandwidth & delay metrics

• With fast convergence

BGP (routing protocol)

• Path-vector exterior gateway protocol

• Used to exchange routing information between autonomous systems

show vlan command

• Displays

  • VLAN IDs

  • Names

  • Associated switch ports

  • Showing network segmentation

show interfaces command

• Displays

  • Interface status

  • Speed

  • Duplex

  • Error counters

  • Not VLAN segmentation details

show mac address-table command

• Displays

  • MAC addresses learned by switch

  • Corresponding switch ports for Layer 2 forwarding

Primary DNS server

• Main DNS server that holds the writable master copy of the zone file

Secondary DNS server

• Holds read-only copy of zone data

• Used for load reduction, redundancy, and availability

Authoritative DNS server

• Directly answers queries for zones it hosts, either primary or secondary

Recursive DNS server

• Resolves names by querying other servers

• Doesn’t store authoritative zone files

Network Metrics

• Represent quantitative value

• Used to determine the best route in routing protocols

VLAN tagging

• 802.1Q process

• Marks Ethernet frames to identify which VLAN they belong to

• Layer 2 of the OSI model

Tunneling

• Encapsulating packets within another protocol

• Done so they can traverse an incompatible/untrusted network

VPN Tunneling Protocols

• IPsec & TLS

• Commonly used tunneling protocols for VPNs

Tunneling uses

• To securely transport VPN traffic across public or untrusted networks

Encapsulation

• Process of adding headers and trailers as data moves from OSI Layer 7 down to Layer 1

De-encapsulation

• Process of removing headers and trailers as data moves from OSI Layer 1 up to Layer 7

Encapsulation vs de-encapsulation direction

• Encapsulation moves Layer 7 to 1 at sender

• De-encapsulation moves Layer 1 to 7 at receiver

Signal Degradation

• Signal quality loss

• Due to

  • Distance

  • Interference

  • Congestion

• in Wi-Fi, often worsens during peak usage hours

NTP

• Network Time Protocol

• Synchronizes clocks over networks

• Millisecond-level accuracy for most systems

PTP

• Precision Time Protocol

• Provides sub-microsecond clock synchronization

• Typically used in industrial, telecom, or financial networks

PTP vs NTP

• NTP offers general-purpose time sync

• PTP provides higher precision using hardware timestamping on supported networks

MAC Spoofing

An attack where a device falsifies its MAC address to impersonate another device on a local network

IP Spoofing

An attack where a packet’s source IP address is forged to impersonate another host

ARP Spoofing

An attack where false ARP messages map an attacker’s MAC address to a legitimate IP address

MAC vs IP vs ARP spoofing difference

• MAC spoofs hardware address

• IP spoofs source IP

• ARP spoofs IP-to-MAC mappings on local networks

IPv4 address Class A range

• First octet 1–126

• Default subnet mask 255.0.0.0 (/8)

• Very large networks

IPv4 address Class B range

• First octet 128–191

• Default subnet mask 255.255.0.0 (/16)

• Medium-sized networks

IPv4 address Class C range

• First octet 192–223

• Default subnet mask 255.255.255.0 (/24)

• Small networks.