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

Question 1

What are the 7 layers of the OSI model in order from Layer 7 down to Layer 1?

Accepted Answer

- Layer 7: **Application**
- Layer 6: **Presentation**
- Layer 5: **Session**
- Layer 4: **Transport**
- Layer 3: **Network**
- Layer 2: **Data Link**
- Layer 1: **Physical**

*Mnemonic*: **A**ll **P**eople **S**eem **T**o **N**eed **D**ata **P**rocessing.

Question 2

How do the 4 layers of the TCP/IP model map to the 7 layers of the OSI model?

Accepted Answer

1. **Application**: Maps to OSI L5–L7 (Session, Presentation, Application).
2. **Transport**: Maps to OSI L4 (Transport).
3. **Internet**: Maps to OSI L3 (Network).
4. **Network Access / Link**: Maps to OSI L1–L2 (Physical, Data Link).

Question 3

What are the default port numbers for `FTP`, `SSH`, `HTTP`, `HTTPS`, and `DNS`?

Accepted Answer

- **FTP**: TCP `20` (Data) & TCP `21` (Control)
- **SSH**: TCP `22`
- **HTTP**: TCP `80`
- **HTTPS**: TCP `443`
- **DNS**: UDP/TCP `53`

Question 4

What are the default port numbers for `SMTP`, `POP3`, `IMAP`, and `RDP`?

Accepted Answer

- **SMTP**: TCP `25` (Plaintext) / `587` (Submission)
- **POP3**: TCP `110` (Unencrypted) / `995` (SSL/TLS)
- **IMAP**: TCP `143` (Unencrypted) / `993` (SSL/TLS)
- **RDP**: TCP/UDP `3389`

Question 5

What are the private IPv4 address ranges specified by RFC 1918?

Accepted Answer

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

Question 6

How do you calculate the number of usable host IP addresses in an IPv4 subnet given a prefix length $n$?

Accepted Answer

The formula for usable host IPs is:
$$	ext{Usable Hosts} = 2^{(32 - n)} - 2$$

The $- 2$ accounts for the **Network ID** (host bits all 0s) and the **Broadcast Address** (host bits all 1s).

Question 7

What is the length of an IPv6 address, and what prefix identifies a Link-Local IPv6 address?

Accepted Answer

An IPv6 address is **128 bits** long (written as 8 hex groups separated by colons).

Link-Local IPv6 addresses always start with the prefix `fe80::/10`.

Question 8

What is the key difference between Distance-Vector and Link-State routing protocols?

Accepted Answer

- **Distance-Vector**: Routers share their full routing tables with direct neighbors based on distance/hop count (e.g., `RIP` using max 15 hops).
- **Link-State**: Routers flood connection state info to build a full map of the network topology and compute shortest paths using Dijkstra's algorithm (e.g., `OSPF`).

Question 9

What is `EIGRP` and how does it determine the best path to a destination?

Accepted Answer

**Enhanced Interior Gateway Routing Protocol (EIGRP)** is an advanced distance-vector routing protocol (formerly Cisco proprietary). It uses the **DUAL** (Diffusing Update Algorithm) and a metric based primarily on **Bandwidth** and **Delay**.

Question 10

What is a `VLAN` and what standard is used to tag traffic across a trunk link?

Accepted Answer

A **VLAN** (Virtual Local Area Network) logically partitions a physical switch into separate broadcast domains.

Trunk lines carry traffic for multiple VLANs using the **IEEE 802.1Q** frame tagging standard.

Question 11

What is the primary function of Spanning Tree Protocol (`STP`, IEEE 802.1D)?

Accepted Answer

**STP** prevents switching loops and broadcast storms on redundant Layer 2 networks by selectively placing switch ports into blocking or forwarding states.

Question 12

Summarize the key differences between the wireless standards `802.11g`, `802.11n`, `802.11ac`, and `802.11ax`.

Accepted Answer

- **802.11g**: 2.4 GHz | Max 54 Mbps
- **802.11n (Wi-Fi 4)**: 2.4 / 5 GHz | Max 600 Mbps (MIMO introduction)
- **802.11ac (Wi-Fi 5)**: 5 GHz | Max ~6.9 Gbps (MU-MIMO)
- **802.11ax (Wi-Fi 6/6E)**: 2.4 / 5 / 6 GHz | Max ~9.6 Gbps (OFDMA)

Question 13

What is the difference between WPA2/WPA3 Personal and Enterprise modes?

Accepted Answer

- **Personal (PSK)**: Uses a shared pre-shared key (passphrase) for all connecting clients.
- **Enterprise**: Uses IEEE 802.1X with a centralized **RADIUS** server so each user authenticates with unique credentials.

Question 14

Compare Star, Full Mesh, and Bus network topologies.

Accepted Answer

- **Star**: Central switch/hub connects all endpoints (easy to expand, central point of failure).
- **Full Mesh**: Every node connects directly to every other node. Uses $\frac{n(n-1)}{2}$ links (maximum redundancy, expensive).
- **Bus**: All nodes share a single coaxial backbone trunk (vulnerable to trunk line cuts).

Question 15

What is the difference between Layer 2 Switches and Layer 3 Routers?

Accepted Answer

- **Layer 2 Switch**: Uses **MAC addresses** to forward data frames within a local network (LAN).
- **Layer 3 Router**: Uses **IP addresses** to forward data packets across different networks (WAN/subnets).

Question 16

What is an Access Control List (`ACL`) and what is the 'Implicit Deny' rule?

Accepted Answer

An **ACL** is a sequential list of rules configured on a router/firewall to permit or deny packets based on criteria (IP, port, protocol).

**Implicit Deny** is an automatic rule at the end of an ACL that drops any traffic not explicitly allowed by preceding rules.

Question 17

What is the core difference between a Stateless Firewall and a Stateful Firewall?

Accepted Answer

- **Stateless**: Evaluates packets individually against rules without keeping track of previous traffic context.
- **Stateful**: Tracks active active connections (state table) and automatically permits safe return traffic belonging to an established session.

Question 18

What are the four steps of the DHCP process for acquiring an IP address?

Accepted Answer

The **DORA** process:
1. **D**iscover: Client broadcasts to find a DHCP server.
2. **O**ffer: DHCP server offers an available IP address configuration.
3. **R**equest: Client requests the offered IP.
4. **A**cknowledge: Server confirms the lease to the client.

Question 19

What are the functions of DNS record types `A`, `AAAA`, `CNAME`, `MX`, and `PTR`?

Accepted Answer

- **A**: Maps a domain name to an IPv4 address.
- **AAAA**: Maps a domain name to an IPv6 address.
- **CNAME**: Maps an alias domain name to a canonical domain name.
- **MX**: Identifies the mail server for receiving email.
- **PTR**: Reverse lookup mapping an IP address to a domain name.

Question 20

What is the difference between ARP Spoofing and DNS Poisoning?

Accepted Answer

- **ARP Spoofing**: Operates at **Layer 2**; sends fake ARP responses to link a target IP to an attacker's MAC address on the local network.
- **DNS Poisoning**: Operates at **Layer 7**; corrupts a DNS cache with fake IP records to redirect traffic to malicious websites.

CompTIA Network+ (N10-008) - Network Topologies, Protocols & Security Fundamentals

Cards in this deck

Related Flashcard Sets

HSK 1 - Basic Chinese Vocabulary, Pinyin & Character Recognition

Functional Programming - Immutability, Pure Functions & Higher-Order Functions

Neuroscience - Neuroanatomy & Brain Function

Microsoft Azure Administrator (AZ-104) - Compute, Storage & Networking