📡 L2_L7_STANDARDS // NETWORKING

Subnet bounds, layer interactions, frame translations, transceivers, and DHCP mappings.

NOC CONTROL

CIDR Subnet & Mask Calculator

IPV4 SUBNETTING

Target IP / CIDR Prefix:

Network Address 10.240.84.192 / 27

Subnet Mask 255.255.255.224

Broadcast Address 10.240.84.223

Usable Host Pool 30 Hosts

Usable Host Range:

10.240.84.193 ➔ 10.240.84.222

Wildcard: 0.0.0.31

Binary Mask: 11111111.11111111.11111111.11100000

Protocol Anatomy: "ping google.com"

DEEP PACKET FLOW

Layer 3 (Network)

Local Socket & Route Inspection

Kernel Socket / Routing Table

User executes 'ping google.com'. The ICMP binary creates a raw socket socket(AF_INET, SOCK_RAW, IPPROTO_ICMP). The OS checks local host routing rules ('ip route') to determine the outgoing interface and default gateway IP.

Inspected Frame Header / Packet Payload: Local Source: 10.240.0.45 | Target Domain: google.com | Socket: AF_INET (RAW)

Stage 1 of 7

Optical Transceiver & DOM Diagnostics

L1 / L2 HARDWARE

Select Transceiver Form Factor:

Speed Rating: 10 Gbps

Channel Lanes: 1 Channel

Wavelength Options: 850nm (SR) / 1310nm (LR)

Physical Interface: LC Duplex

Digital Optical Monitoring (DOM) Power Converter

Laser Rx Power (Milliwatts - mW):

Calculated Decibel-Milliwatts:

-4.20 dBm

DOM Health Status GOOD (STANDARD OPERATIONAL)

Interactive OSI Model

Select a layer to inspect protocol bindings and physical equipment.

Layer 7: Application

L7 SPEC

Functional Responsibility:

End-user interfaces and network-aware application processes.

Key Protocols

HTTP, DNS, DHCP, SSH, FTP, SMTP

Physical Equipment

Layer 7 Web Application Firewalls, Application Load Balancers

Interview Scenario Reference

Q: Explain DHCP's port usage under UDP transport.
A: DHCP utilizes UDP. Clients send packets from Source Port 68 to Destination Port 67 (Server). Servers reply from Source Port 67 to Destination Port 68 (Client).

DHCP State Machine: The DORA Process

Technician Laptop MAC: 00:0a:95:9d:68:16

📢 BROADCAST FRAME

Source IP: 0.0.0.0:68 ➔ Destination IP: 255.255.255.255:67

Action: Client broadcasts network parameter search query across local Layer 2 segment.

DHCP Server Gateway: 10.0.0.1