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

Question 1

OSI Model (7 Layers)

Accepted Answer

1. **Physical**: Bits, electrical/optical signals, cables.
2. **Data Link**: Frames, MAC addressing, switches.
3. **Network**: Packets, IP addresses, routers.
4. **Transport**: Segments (TCP) / Datagrams (UDP), port numbers, flow control.
5. **Session**: Session setup, maintenance, and teardown.
6. **Presentation**: Data formatting, encryption, compression.
7. **Application**: Network services for applications (HTTP, FTP, SMTP).

Question 2

Common Ports: Remote Access & File Transfer

Accepted Answer

• **FTP**: Ports `20`/`21` (Unencrypted file transfer)
• **SSH / SFTP**: Port `22` (Encrypted CLI & secure file transfer)
• **Telnet**: Port `23` (Unencrypted text remote CLI)
• **RDP**: Port `3389` (Remote Desktop Protocol)

Question 3

Common Ports: Web, IP Assignment & Name Resolution

Accepted Answer

• **DNS**: Port `53` (Domain name to IP resolution; UDP/TCP)
• **DHCP**: Ports `67` (server) / `68` (client) (Dynamic IP allocation)
• **HTTP**: Port `80` (Unencrypted web traffic)
• **HTTPS**: Port `443` (TLS/SSL encrypted web traffic)

Question 4

Common Ports: Mail & Network Management

Accepted Answer

• **SMTP**: Port `25` (Sending email between servers)
• **POP3**: Port `110` (Retrieving email, downloads to client)
• **IMAP**: Port `143` (Retrieving email, syncs with server)
• **SNMP**: Ports `161`/`162` (Network device monitoring)

Question 5

IPv4 Subnetting & Host Calculation

Accepted Answer

Subnetting divides IP networks into smaller subnetworks.
• **Formula for usable hosts**: $2^{(32 - n)} - 2$, where $n$ is the prefix length (CIDR).
• *Example*: A `/24` subnet has $2^{8} - 2 = 254$ usable host IP addresses because 2 addresses are reserved (Network ID and Broadcast ID).

Question 6

IPv6 Address Structure & Features

Accepted Answer

• **Format**: 128-bit address formatted as 8 groups of 4 hexadecimal digits (e.g., `2001:0db8:85a3::8a2e:0370:7334`).
• **Types**: **Unicast** (one-to-one), **Multicast** (one-to-many), **Anycast** (one-to-nearest).
• **Key Feature**: IPv6 does **not** use broadcast traffic (uses multicast instead).

Question 7

T568A vs. T568B Wiring Standards

Accepted Answer

Standards for terminating RJ45 Ethernet twisted-pair cables:
• **T568A Pinouts**: White/Green, Green, White/Orange, Blue, White/Blue, Orange, White/Brown, Brown.
• **T568B Pinouts**: White/Orange, Orange, White/Green, Blue, White/Blue, Green, White/Brown, Brown.
• **Crossover Cable**: T568A on one end, T568B on the other.

Question 8

Copper Cabling Categories

Accepted Answer

• **Cat 5e**: 1 Gbps up to 100 meters (100 MHz).
• **Cat 6**: 10 Gbps up to 55 meters; 1 Gbps up to 100 meters (250 MHz).
• **Cat 6a**: 10 Gbps up to 100 meters with improved shielding (500 MHz).

Question 9

Single-Mode vs. Multi-Mode Fiber

Accepted Answer

• **Single-Mode Fiber (SMF)**: Small core (~9 microns), laser light source, long distances (up to 40+ km), low attenuation, higher cost.
• **Multi-Mode Fiber (MMF)**: Larger core (50–62.5 microns), LED light source, shorter distances (up to ~550m), susceptible to modal dispersion.

Question 10

Physical Network Topologies

Accepted Answer

• **Star**: Central switch/hub; single point of failure at center (most common).
• **Mesh**: High redundancy. Full mesh formula for links: $\frac{n(n-1)}{2}$.
• **Bus**: Single central backbone cable terminated at both ends.
• **Ring**: Circular data traffic; single break disrupts entire network unless dual-ringed.

Question 11

TCP vs. UDP Protocols

Accepted Answer

• **TCP (Transmission Control Protocol)**: Connection-oriented (3-way handshake: `SYN` -> `SYN-ACK` -> `ACK`), reliable, guarantees ordered delivery, performs error checking and flow control.
• **UDP (User Datagram Protocol)**: Connectionless, lightweight, low-latency, non-guaranteed delivery (used for streaming, VoIP, DNS).

Question 12

Distance-Vector vs. Link-State Routing

Accepted Answer

• **Distance-Vector** (e.g., RIP): Routes based on distance (hop count) and direction; advertises full routing tables to direct neighbors.
• **Link-State** (e.g., OSPF): Routes based on link status, speed, and cost; builds a full topology map of the network; fast convergence.

Question 13

Border Gateway Protocol (BGP)

Accepted Answer

• **Type**: Path-Vector exterior gateway protocol (EGP).
• **Function**: Routes data between distinct Autonomous Systems (AS) across the global Internet.
• **Protocol**: Runs over TCP port `179`.

Question 14

IEEE 802.11 Wireless Standards

Accepted Answer

• **802.11b**: 2.4 GHz | Max 11 Mbps
• **802.11g**: 2.4 GHz | Max 54 Mbps
• **802.11n (Wi-Fi 4)**: 2.4 & 5 GHz | Max 600 Mbps (Introduced MIMO)
• **802.11ac (Wi-Fi 5)**: 5 GHz only | Max 3.46 Gbps (MU-MIMO, Beamforming)
• **802.11ax (Wi-Fi 6/6E)**: 2.4, 5, & 6 GHz | Max 9.6 Gbps (OFDMA)

Question 15

Troubleshooting Tools: `ping` vs. `traceroute`

Accepted Answer

• `ping`: Uses ICMP Echo Request/Reply messages to verify basic network connectivity and measure round-trip latency.
• `traceroute` (Linux/macOS) / `tracert` (Windows): Uses ICMP/UDP with incremental Time-To-Live (TTL) values to map host hops along a path.

Question 16

Troubleshooting Tools: `netstat`, `nslookup`, & `dig`

Accepted Answer

• `netstat`: Displays active network connections, listening ports, routing tables, and interface statistics.
• `nslookup`: CLI tool to query DNS servers for IP address mapping and DNS records.
• `dig`: Advanced CLI tool (Linux/macOS) for querying DNS records and troubleshooting name resolution.

Question 17

Network Address Translation (NAT) Types

Accepted Answer

• **Static NAT**: One-to-one mapping of a private IP to a public IP.
• **Dynamic NAT**: Maps private IPs to a pool of available public IPs.
• **PAT (Port Address Translation / NAT Overload)**: Maps multiple private IPs to a single public IP using unique source port numbers.

Question 18

VLANs & IEEE 802.1Q Trunking

Accepted Answer

• **VLAN (Virtual LAN)**: Logically segments physical switches into separate broadcast domains at Layer 2.
• **802.1Q**: The standard trunking protocol that inserts a 4-byte VLAN tag into the Ethernet frame header to carry traffic for multiple VLANs over a single link.

Question 19

Stateless vs. Stateful Firewalls

Accepted Answer

• **Stateless Firewall**: Filters network traffic based purely on static rules (IP addresses, ports) without tracking connection states.
• **Stateful Firewall**: Tracks the context and state of active connections (e.g., TCP handshakes) in a state table, dynamically allowing return traffic.

Question 20

Address Resolution Protocol (ARP) vs. NDP

Accepted Answer

• **ARP (IPv4)**: Resolves known IP addresses to unknown hardware MAC addresses using Layer 2 broadcast requests.
• **NDP (IPv6)**: Neighbor Discovery Protocol operates via ICMPv6 to perform IPv6-to-MAC resolution, router discovery, and autoconfiguration (replaces ARP).

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

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