CompTIA Network+ (N10-008) - Network Fundamentals & Security Flashcards

Question 1

TCP/IP Model vs. OSI Model Mapping

Accepted Answer

The **TCP/IP Model** consists of 4 layers that map to the 7-layer **OSI Model**:
- **Application Layer**: Maps to OSI Layers 5, 6, and 7 (Session, Presentation, Application).
- **Transport Layer**: Maps to OSI Layer 4 (Transport).
- **Internet Layer**: Maps to OSI Layer 3 (Network).
- **Network Access Layer**: Maps to OSI Layers 1 and 2 (Physical, Data Link).

Question 2

Domain Name System (DNS) & Port

Accepted Answer

Resolves human-readable FQDNs (e.g., `example.com`) to IP addresses.
- **Port**: UDP/TCP port `53` (UDP for queries, TCP for zone transfers).
- **Key Records**: `A` (IPv4), `AAAA` (IPv6), `CNAME` (Alias), `MX` (Mail), `TXT` (Verification/SPF/DKIM).

Question 3

DHCP DORA Process

Accepted Answer

The 4-step process used by DHCP to dynamically assign IP addresses:
1. **Discover**: Client broadcasts a request for a DHCP server (UDP `67`).
2. **Offer**: Server offers an IP address to the client (UDP `68`).
3. **Request**: Client requests the offered IP address.
4. **Acknowledge**: Server confirms and leases the IP address.

Question 4

Address Resolution Protocol (ARP)

Accepted Answer

Resolves a known IPv4 address to an unknown Layer 2 **MAC address** on a local network segment.
- `arp -a` displays the local ARP cache.
- Neighbor Discovery Protocol (**NDP**) serves this function in IPv6 using ICMPv6.

Question 5

Internet Control Message Protocol (ICMP)

Accepted Answer

A Network Layer (Layer 3) protocol used for IP error reporting and operational feedback.
- Leveraged by utilities like `ping` (Echo Request/Reply) and `traceroute`.
- Does not use TCP or UDP port numbers.

Question 6

Ethernet Cabling Standards (Cat 5e, Cat 6, Cat 6a)

Accepted Answer

- **Cat 5e**: Up to 1 Gbps at 100 meters (100 MHz).
- **Cat 6**: Up to 10 Gbps up to 55 meters; 1 Gbps at 100 meters (250 MHz).
- **Cat 6a**: Up to 10 Gbps at full 100 meters (500 MHz).

Question 7

T568B Wiring Standard Pinout

Accepted Answer

The color order for pins 1 through 8 in the T568B standard:
1. White/Orange
2. Orange
3. White/Green
4. Blue
5. White/Blue
6. Green
7. White/Brown
8. Brown

Question 8

Full Mesh Topology Connection Formula

Accepted Answer

In a **Full Mesh** network topology, every node connects to every other node directly. The total number of connections ($N$) required for $n$ devices is:
$$N = \frac{n(n - 1)}{2}$$
This provides high redundancy but scales exponentially in cost and complexity.

Question 9

Wi-Fi Standards Summary (802.11ax vs. 802.11ac)

Accepted Answer

- **802.11ac (Wi-Fi 5)**: Operates exclusively in the 5 GHz band; uses MU-MIMO; max theoretical speed ~6.9 Gbps.
- **802.11ax (Wi-Fi 6/6E)**: Operates in 2.4 GHz, 5 GHz, and 6 GHz (6E); uses OFDMA and bi-directional MU-MIMO; max speed ~9.6 Gbps.

Question 10

WPA3 & Simultaneous Authentication of Equals (SAE)

Accepted Answer

**WPA3** enhances wireless security by replacing WPA2's Pre-Shared Key (PSK) handshake with **SAE** (a variant of Dragonfly Key Exchange).
- Prevents offline dictionary attacks.
- Provides **Forward Secrecy**, protecting past traffic even if the password is leaked later.

Question 11

Virtual LAN (VLAN) & IEEE 802.1Q

Accepted Answer

A **VLAN** logically segment networks at Layer 2 to isolate broadcast domains.
- **IEEE 802.1Q** is the standard protocol for VLAN tagging on trunk links, adding a 4-byte header to the Ethernet frame containing a 12-bit VLAN ID (1–4094).

Question 12

Routing Protocols: Distance-Vector vs. Link-State

Accepted Answer

- **Distance-Vector** (e.g., RIP, EIGRP): Shares routing tables with direct neighbors based on distance (hop count or metric). Uses Bellman-Ford or DUAL algorithms.
- **Link-State** (e.g., OSPF, IS-IS): Builds a complete map (topological database) of the network using Shortest Path First (Dijkstra's) algorithm.

Question 13

Stateful vs. Stateless Firewalls

Accepted Answer

- **Stateless Firewall**: Filters traffic based solely on static rules (source/destination IP, port, protocol) without tracking connection state.
- **Stateful Firewall**: Tracks active connections in a state table, allowing return traffic automatically if the initial connection was permitted.

Question 14

Intrusion Detection System (IDS) vs. Intrusion Prevention System (IPS)

Accepted Answer

- **IDS**: Passive monitor placed out-of-band via a SPAN/TAP port; detects malicious activity and generates alerts without dropping traffic.
- **IPS**: Active inline device; analyzes live traffic and actively blocks or drops detected threats in real-time.

Question 15

Usable IPv4 Hosts Calculation

Accepted Answer

For a given CIDR subnet mask with $h$ host bits ($h = 32 - 	ext{CIDR prefix}$), the number of usable host IP addresses is:
$$	ext{Usable Hosts} = 2^h - 2$$
*(Subtracting 2 for the Network ID and Broadcast Address).* Example: A `/24` network has $h = 8$, yielding $2^8 - 2 = 254$ usable hosts.

Question 16

`ping` and `traceroute` / `tracert` Commands

Accepted Answer

- **`ping`**: Tests Layer 3 reachability using ICMP Echo Request/Reply.
- **`traceroute` (Linux/macOS) / `tracert` (Windows)**: Identifies the path/hops to a remote host by incrementally increasing the IP packet's **Time to Live (TTL)** value starting at 1.

Question 17

`netstat` / `ss` Troubleshooting Tool

Accepted Answer

Command-line tools used to display network connections, routing tables, interface statistics, and listening ports.
- Common flags: `netstat -ano` (Windows: displays numerical addresses and process IDs) or `ss -tulpn` (Linux).

Question 18

`nslookup` vs. `dig` Tools

Accepted Answer

- **`nslookup`**: Cross-platform CLI utility used for querying DNS to obtain domain name or IP address mappings.
- **`dig` (Domain Information Groper)**: Advanced Linux/macOS tool that provides detailed DNS query/response outputs, useful for troubleshooting DNS records.

Question 19

Zero Trust Security Architecture

Accepted Answer

A security model based on the principle of **"Never Trust, Always Verify."**
- Requires strict identity verification for every user and device attempting to access resources on a network, regardless of whether they are inside or outside the network perimeter.

Question 20

Security Information and Event Management (SIEM)

Accepted Answer

A centralized platform that aggregates, correlates, and analyzes security log data from multiple sources (firewalls, servers, routers) across an enterprise network in real-time to detect threats and ensure compliance.

CompTIA Network+ (N10-008) - Network Fundamentals & Security

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