Network Reference Guide

Comprehensive networking concepts, IPv4 addressing, subnetting, and conversion reference.

IPv4 Addressing Fundamentals

Key Concepts:

32-bit address system - Four octets (8 bits each)
CIDR notation - Classless Internet Domain Routing
Network and Host portions - Determined by subnet mask
Reserved addresses - Network and broadcast addresses

Host Calculation Formula:

Hosts = 2^{(32 - CIDR)} - 2
Subtract 2 for network and broadcast addresses

Host Calculator

Enter CIDR (e.g., 24):

Results:

Total Addresses: -

Usable Hosts: -

Subnet Mask: -

Host Bits: -

CIDR to Subnet Converter

Enter Network (e.g., 192.168.1.0/24):

Network Details:

Network Address: -

Broadcast Address: -

First Host: -

Last Host: -

Subnet Mask: -

Subnetting Example: 192.168.0.0/24

Network Information:

Network Address: 192.168.0.0
CIDR Notation: /24
Subnet Mask: 255.255.255.0
Broadcast Address: 192.168.0.255

Host Calculation:

Hosts = 2^(32-24) - 2
Hosts = 2^8 - 2
Hosts = 256 - 2
Hosts = 254

Usable Host Range: 192.168.0.1 - 192.168.0.254

CIDR Subnet Reference Table

CIDR	Subnet Mask	Binary Mask	Hosts	Networks	Class
/8	255.0.0.0	11111111.00000000.00000000.00000000	16,777,214	256	A
/16	255.255.0.0	11111111.11111111.00000000.00000000	65,534	65,536	B
/24	255.255.255.0	11111111.11111111.11111111.00000000	254	16,777,216	C
/25	255.255.255.128	11111111.11111111.11111111.10000000	126	33,554,432	-
/26	255.255.255.192	11111111.11111111.11111111.11000000	62	67,108,864	-
/27	255.255.255.224	11111111.11111111.11111111.11100000	30	134,217,728	-
/28	255.255.255.240	11111111.11111111.11111111.11110000	14	268,435,456	-
/29	255.255.255.248	11111111.11111111.11111111.11111000	6	536,870,912	-
/30	255.255.255.252	11111111.11111111.11111111.11111100	2	1,073,741,824	Point-to-Point
/31	255.255.255.254	11111111.11111111.11111111.11111110	2	2,147,483,648	Point-to-Point
/32	255.255.255.255	11111111.11111111.11111111.11111111	1	4,294,967,296	Host Route

Number System Conversions

Common Number Systems:

Binary (Base 2): 0, 1
Octal (Base 8): 0-7
Decimal (Base 10): 0-9
Hexadecimal (Base 16): 0-9, A-F

Powers of 2 (Networking):

2¹ = 2
2² = 4
2³ = 8
2⁴ = 16
2⁸ = 256

Base Conversion Reference

Decimal	Binary	Octal	Hexadecimal
0	0000	0	0
1	0001	1	1
2	0010	2	2
3	0011	3	3
4	0100	4	4
5	0101	5	5
6	0110	6	6
7	0111	7	7
8	1000	10	8
9	1001	11	9
10	1010	12	A
11	1011	13	B
12	1100	14	C
13	1101	15	D
14	1110	16	E
15	1111	17	F
255	11111111	377	FF

Package Management

Homebrew (macOS/Linux):

# Install package
brew install <package_name>

# Update Homebrew
brew update

# Upgrade packages
brew upgrade

# Search packages
brew search <package_name>

APT (Ubuntu/Debian):

# Install package
sudo apt install <package_name>

# Update package list
sudo apt update

# Upgrade packages
sudo apt upgrade

# Search packages
apt search <package_name>

YUM/DNF (RedHat/CentOS):

# Install package
sudo yum install <package_name>

# Update packages
sudo yum update

# Search packages
yum search <package_name>

# DNF (newer)
sudo dnf install <package_name>

Essential Network Tools & Commands

Connectivity Testing:

# Ping test
ping google.com

# Traceroute
traceroute google.com
# Windows: tracert google.com

# Port scanning
nmap -p 80,443 google.com

# DNS lookup
nslookup google.com
dig google.com

Network Configuration:

# Show IP configuration
ip addr show
# Windows: ipconfig /all

# Show routing table
ip route show
# Windows: route print

# Show network connections
netstat -tuln
ss -tuln

# Show ARP table
arp -a