CompTIA Network+ (N10-008) - Networking Fundamentals & Subnetting Flashcards

Question 1

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

Accepted Answer

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

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

Question 2

Identify the standard port numbers and transport protocols for core remote access and web services: SSH, SFTP, Telnet, HTTP, and HTTPS.

Accepted Answer

- `SSH` / `SFTP`: Port **22** (TCP)
- `Telnet`: Port **23** (TCP)
- `HTTP`: Port **80** (TCP)
- `HTTPS`: Port **443** (TCP)

Question 3

What are the default port numbers and transport protocols for DNS, DHCP, NTP, and BGP?

Accepted Answer

- `DNS`: Port **53** (UDP for client queries, TCP for zone transfers)
- `DHCP`: Ports **67** (Server) & **68** (Client) (UDP)
- `NTP`: Port **123** (UDP)
- `BGP`: Port **179** (TCP)

Question 4

Identify the standard ports for email and directory service protocols: SMTP, POP3, IMAP, and LDAPS.

Accepted Answer

- `SMTP`: Port **25** (TCP)
- `POP3`: Port **110** (TCP)
- `IMAP`: Port **143** (TCP)
- `LDAPS` (LDAP Secure): Port **636** (TCP)

Question 5

What is the formula to calculate the number of usable host IP addresses in an IPv4 subnet given a CIDR notation `/n`?

Accepted Answer

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

Where:
- $32 - n$ represents the number of host bits.
- Subtract **2** to account for the **Network ID** (all host bits `0`) and the **Broadcast Address** (all host bits `1`).

Question 6

For a `/26` IPv4 prefix, what is the subnet mask, total IP addresses, and total usable host addresses?

Accepted Answer

- **Subnet Mask**: `255.255.255.192`
- **Host Bits**: $32 - 26 = 6$ bits
- **Total IP Addresses**: $2^6 = 64$
- **Usable Host Addresses**: $64 - 2 = 62$

Question 7

Given the IP address `192.168.1.35/28`, determine the Network ID and the Broadcast Address.

Accepted Answer

- **Block Size**: $2^{(32-28)} = 2^4 = 16$
- Subnet increments: `.0`, `.16`, `.32`, `.48`...
- `192.168.1.35` lies between `.32` and `.47`.

- **Network ID**: `192.168.1.32`
- **Broadcast Address**: `192.168.1.47`
- **Usable Host Range**: `192.168.1.33` - `192.168.1.46`

Question 8

Compare Cat 5e, Cat 6, and Cat 6a Ethernet cables by max data throughput and distance limitations.

Accepted Answer

- **Cat 5e**: Up to **1 Gbps** @ 100 MHz (Max distance: 100 meters)
- **Cat 6**: Up to **10 Gbps** @ 250 MHz (Max distance: 55 meters; 1 Gbps up to 100 meters)
- **Cat 6a**: Up to **10 Gbps** @ 500 MHz (Max distance: 100 meters)

Question 9

What are the wire color sequences for the T568A and T568B RJ45 wiring standards?

Accepted Answer

- **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

*Note*: Pin pairs 1-2 (Green in A) and 3-6 (Orange in A) swap places between the two standards.

Question 10

Map Wi-Fi standards Wi-Fi 4, Wi-Fi 5, and Wi-Fi 6 to their IEEE standard names and operating frequencies.

Accepted Answer

- **Wi-Fi 4** (`802.11n`): Operates at **2.4 GHz** and **5 GHz** (up to 600 Mbps)
- **Wi-Fi 5** (`802.11ac`): Operates at **5 GHz** only (up to 6.9 Gbps)
- **Wi-Fi 6** (`802.11ax`): Operates at **2.4 GHz**, **5 GHz**, and **6 GHz** (Wi-Fi 6E) (up to 9.6 Gbps)

Question 11

What are the key differences between the 2.4 GHz and 5 GHz wireless frequency bands?

Accepted Answer

- **2.4 GHz Band**: Longer coverage range and better wall penetration, but slower speeds and high channel congestion. Has 11 US channels with only **3 non-overlapping channels** (`1`, `6`, `11`).
- **5 GHz Band**: Faster data rates and shorter range with poorer penetration. Provides **24+ non-overlapping channels**, resulting in significantly lower interference.

Question 12

Compare the core characteristics of dynamic routing protocols: OSPF vs. BGP.

Accepted Answer

- **OSPF (Open Shortest Path First)**: An **Interior Gateway Protocol (IGP)** using a **Link-State** algorithm. Best for routing within a single Autonomous System (AS). Uses cost (bandwidth) as metric.
- **BGP (Border Gateway Protocol)**: An **Exterior Gateway Protocol (EGP)** using a **Path-Vector** algorithm. Best for routing traffic *between* different Autonomous Systems across the Internet.

Question 13

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

Accepted Answer

- **Distance-Vector** (e.g., `RIP`): Routers send their entire routing table to directly connected neighbors at periodic intervals. Routes are calculated using hop counts or simple vectors.
- **Link-State** (e.g., `OSPF`, `IS-IS`): Routers flood link-state advertisements (LSAs) throughout the network to build a complete map (topology database). Shortest paths are computed using Dijkstra's algorithm.

Question 14

What are the rules for zero compression and leading zero omission in IPv6 addresses?

Accepted Answer

1. **Omit Leading Zeros**: Leading zeros in any 16-bit hextek can be dropped (e.g., `:0045:` becomes `:45:`).
2. **Double Colon Compression (`::`)**: A single contiguous sequence of all-zero hexteks can be replaced by `::`.

*Constraint*: `::` can only be used **once** per IPv6 address to avoid ambiguity.

Question 15

Identify the IPv6 address prefixes for Loopback, Link-Local, Unique Local, and Global Unicast addresses.

Accepted Answer

- **Loopback**: `::1/128` (IPv4: `127.0.0.1`)
- **Link-Local**: `fe80::/10` (Non-routable; restricted to local segment)
- **Unique Local**: `fc00::/7` (IPv4 Private IP equivalent)
- **Global Unicast**: `2000::/3` (IPv4 Public IP equivalent)

Question 16

List the three RFC 1918 private IPv4 address ranges along with their default CIDR masks.

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 17

What is APIPA, what IPv4 range does it assign, and under what conditions is it triggered?

Accepted Answer

**APIPA** (Automatic Private IP Addressing) auto-assigns an IP in the range `169.254.0.1` to `169.254.255.254` (`169.254.0.0/16`) when a client is configured for DHCP but fails to contact a DHCP server. It allows local network communications but is non-routable across gateways.

Question 18

Compare TCP and UDP based on connection state, reliability, overhead, and common use cases.

Accepted Answer

- **TCP (Transmission Control Protocol)**: Connection-oriented (uses 3-way handshake: `SYN` $\rightarrow$ `SYN-ACK` $\rightarrow$ `ACK`), reliable, guarantees ordered delivery via sequencing, higher overhead. Used for web browsing, email, file transfers.
- **UDP (User Datagram Protocol)**: Connectionless, unreliable, best-effort delivery, low overhead. Used for real-time services like streaming, VoIP, gaming, and DNS lookup.

Question 19

What is the difference between a MAC address and an IP address in networking?

Accepted Answer

- **MAC Address**: A 48-bit physical address assigned at the Layer 2 Data Link layer, burned into the Network Interface Card (NIC). Format: `XX:XX:XX:YY:YY:YY` (OUI + Device Identifier).
- **IP Address**: A 32-bit (IPv4) or 128-bit (IPv6) logical address assigned at Layer 3 Network layer, used to route packets across multiple networks.

Question 20

Match each network CLI tool to its primary function: `ping`, `traceroute` / `tracert`, `netstat`, and `nslookup` / `dig`.

Accepted Answer

- `ping`: Tests Layer 3 reachability to a remote host using ICMP Echo Requests.
- `traceroute` (Linux/macOS) / `tracert` (Windows): Traces the path and measures latency across each router hop to a destination.
- `netstat`: Displays active socket connections, listening ports, and host routing tables.
- `nslookup` / `dig`: Queries DNS servers to resolve hostnames to IP addresses or inspect DNS record details.

CompTIA Network+ (N10-008) - Networking Fundamentals & Subnetting

Cards in this deck

Related Flashcard Sets

JLPT N2 - Upper-Intermediate Japanese Kanji, Grammar & Expressions

HSK 4 - Intermediate Chinese Vocabulary & Grammar

CompTIA Network+ (N10-008) - Networking Fundamentals & Protocols

Waterloo CS488 - Introduction to Computer Graphics