CompTIA Network+ (N10-008) - Networking Concepts & Infrastructure Flashcards

Question 1

OSI Model - 7 Layers

Accepted Answer

The 7 layers from top to bottom are:
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical
*(Mnemonic: 'Please Do Not Throw Sausage Pizza Away' - bottom-up)*

Question 2

Star Topology

Accepted Answer

A network topology where every node connects directly to a central networking device (such as a switch or hub). A cable failure only affects the individual device connected, preventing network-wide outages.

Question 3

Mesh Topology (Full vs. Partial)

Accepted Answer

- **Full Mesh**: Every node is connected to every other node, offering maximum redundancy calculated by $\frac{n(n-1)}{2}$ connections.
- **Partial Mesh**: Selected critical nodes are redundantly interconnected to balance cost and redundancy.

Question 4

Twisted Pair Cabling: `Cat5e`, `Cat6`, and `Cat6a`

Accepted Answer

- `Cat5e`: Supports 1 Gbps up to 100 meters (100 MHz bandwidth).
- `Cat6`: Supports 10 Gbps up to 55 meters and 1 Gbps up to 100 meters (250 MHz bandwidth).
- `Cat6a`: Supports 10 Gbps up to 100 meters (500 MHz bandwidth).

Question 5

Single-Mode Fiber (SMF) vs. Multi-Mode Fiber (MMF)

Accepted Answer

- **SMF**: Small core size (~9 microns), uses a laser source; designed for long-distance transmissions (tens of kilometers) with minimal signal attenuation.
- **MMF**: Larger core size (50–62.5 microns), uses LED/laser sources; designed for shorter distances (up to ~550m at 10 Gbps) due to modal dispersion.

Question 6

T568A vs. T568B Wiring Standards

Accepted Answer

RJ45 pinout standards:
- `T568A`: White/Green, Green, White/Orange, Blue, White/Blue, Orange, White/Brown, Brown.
- `T568B`: White/Orange, Orange, White/Green, Blue, White/Blue, Green, White/Brown, Brown.

Question 7

Common Ports: Core Network Services (`DNS`, `DHCP`)

Accepted Answer

- **DNS (Domain Name System)**: `UDP/TCP 53` — Translates human-readable domain names to IP addresses.
- **DHCP (Dynamic Host Configuration Protocol)**: `UDP 67/68` — Dynamically assigns IP addresses, subnet masks, gateways, and DNS servers to hosts.

Question 8

Common Ports: Web Protocols (`HTTP`, `HTTPS`)

Accepted Answer

- **HTTP (Hypertext Transfer Protocol)**: `TCP 80` — Unencrypted web communication.
- **HTTPS (HTTP Secure)**: `TCP 443` — Web communication encrypted using TLS/SSL.

Question 9

Common Ports: Secure & Unsecure Remote Access (`SSH`, `Telnet`)

Accepted Answer

- **SSH (Secure Shell)**: `TCP 22` — Encrypted remote terminal access and secure file transport.
- **Telnet**: `TCP 23` — Unencrypted, legacy remote CLI access (sends credentials in plaintext).

Question 10

Common Ports: File Transfer (`FTP`, `SFTP`, `TFTP`)

Accepted Answer

- **FTP**: `TCP 20/21` — Transfers files with password authentication (unencrypted).
- **SFTP**: `TCP 22` — Secure SSH-based file transfer.
- **TFTP**: `UDP 69` — Simple, lightweight connectionless file transfer (often used for bootstrapping or network firmware updates).

Question 11

IPv4 Address Structure & CIDR Notation

Accepted Answer

A 32-bit binary address written as 4 octets in dotted decimal (e.g., `192.168.1.1`). CIDR notation (e.g., `/24`) indicates the prefix length representing the network bits (a `/24` equals subnet mask `255.255.255.0`, yielding $2^{32-24} - 2 = 254$ usable host addresses).

Question 12

RFC 1918 Private IPv4 Address Ranges

Accepted Answer

- **Class A**: `10.0.0.0` – `10.255.255.255` (`10.0.0.0/8`)
- **Class B**: `172.16.0.0` – `172.31.255.255` (`172.16.0.0/12`)
- **Class C**: `192.168.0.0` – `192.168.255.255` (`192.168.0.0/16`)

Question 13

IPv6 Address Features & Compression Rules

Accepted Answer

A 128-bit address formatted in 8 groups of 4 hexadecimal digits (e.g., `2001:0db8:85a3:0000:0000:8a2e:0370:7334`).
- **Compression Rule 1**: Omit leading zeros in any group (`0db8` -> `db8`).
- **Compression Rule 2**: Replace contiguous groups of all zeros with double colons `::` (can only be used once per address).

Question 14

Wireless Standards: `802.11n`, `802.11ac`, and `802.11ax`

Accepted Answer

- **Wi-Fi 4 (`802.11n`)**: Operates on 2.4 GHz & 5 GHz; introduced MIMO; up to 600 Mbps.
- **Wi-Fi 5 (`802.11ac`)**: Operates on 5 GHz only; introduced MU-MIMO; up to 6.9 Gbps.
- **Wi-Fi 6 / 6E (`802.11ax`)**: Operates on 2.4 GHz, 5 GHz, and 6 GHz; uses OFDMA for dense environments.

Question 15

Wireless Frequencies: 2.4 GHz vs. 5 GHz

Accepted Answer

- **2.4 GHz**: Offers longer range and better wall penetration, but lower speed and higher interference (only 3 non-overlapping channels: 1, 6, 11).
- **5 GHz**: Offers faster data throughput and less interference (24 non-overlapping channels), but shorter range and poorer wall penetration.

Question 16

Wi-Fi Security: WPA2 vs. WPA3

Accepted Answer

- **WPA2**: Uses `AES` with `CCMP`; susceptible to offline dictionary attacks via captured 4-way handshakes.
- **WPA3**: Uses `Simultaneous Authentication of Equals (SAE)` to protect against offline brute-force attacks and provides Forward Secrecy.

Question 17

ARP (Address Resolution Protocol) vs. NDP (Neighbor Discovery Protocol)

Accepted Answer

- **ARP**: Resolves IPv4 addresses to physical MAC addresses on Layer 2.
- **NDP**: Operates via ICMPv6 to replace ARP in IPv6 networks, performing address resolution, router discovery, and auto-configuration (SLAAC).

Question 18

VLAN (Virtual Local Area Network) & IEEE `802.1Q`

Accepted Answer

A VLAN logically segments a physical switch into distinct broadcast domains regardless of physical port location. IEEE `802.1Q` adds a 4-byte tag to the Layer 2 Ethernet frame header to identify the VLAN ID across trunk links.

Question 19

DNS Record Types: `A`, `AAAA`, `CNAME`, `MX`, `PTR`

Accepted Answer

- `A`: Maps domain name to IPv4 address.
- `AAAA`: Maps domain name to IPv6 address.
- `CNAME`: Canonical Name (alias for another domain name).
- `MX`: Mail Exchange (specifies mail servers for the domain).
- `PTR`: Pointer record (used for Reverse DNS lookups, IP to domain).

Question 20

Stateful vs. Stateless Firewalls

Accepted Answer

- **Stateful Firewall**: Tracks active connection states (TCP 3-way handshake) and dynamically allows return traffic for established sessions.
- **Stateless Firewall**: Evaluates traffic on a packet-by-packet basis against Access Control Lists (ACLs) without tracking connection state.

Question 21

TCP vs. UDP Protocol Characteristics

Accepted Answer

- **TCP (Transmission Control Protocol)**: Connection-oriented, reliable, guarantees packet delivery and ordering via flow control and 3-way handshakes (`SYN`, `SYN-ACK`, `ACK`).
- **UDP (User Datagram Protocol)**: Connectionless, unreliable, low-overhead; preferred for real-time traffic like VoIP and streaming.

CompTIA Network+ (N10-008) - Networking Concepts & Infrastructure

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