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Networking Toolbox

The sysadmin's Swiss Army knife

Networking Toolbox

Subnetting

IPv4 Subnet Calculator
IPv6 Subnet Calculator
VLSM Calculator
Supernet Calculator
Subnet Planner

CIDR Tools

CIDR Masks

CIDR → Mask
Mask → CIDR

Set Operations

Difference (A - B)
Overlap (A ∩ B)
Contains (A ⊆ B)

More

CIDR Summarizer
CIDR Split
Next Available Subnet
Free Space Finder
CIDR Deaggregate
CIDR Compare
CIDR Allocator
CIDR Alignment
Wildcard Mask Converter

IP Tools

Number Formats

Format Representations

Address Calculations

IP Distance Calculator
Nth IP Calculator
Random IP Generator
IP Regex Generator
IP Address Validator
IP Enumerate

IPv6 Notation

IPv6 Expand
IPv6 Compress
IPv6 Normalizer
IPv6 Zone ID Handler
IPv6 Solicited-Node
IPv6 Teredo Parser
IPv6 NAT64 Translator

IP Families

IPv4 → IPv6
IPv6 → IPv4

Address Generation

EUI-64 Converter
ULA Generator

DNS

DNS Generators

PTR Generator

Reverse DNS

PTR Generator
Reverse Zone Generator
Reverse Zones Calculator
PTR Sweep Planner

Record Generators

A/AAAA Bulk Generator
CNAME Builder
MX Record Planner
SRV Record Builder
TXT Record Escape Tool
SPF Policy Builder
DKIM Key Generator
DMARC Policy Builder
CAA Record Builder
TLSA Generator
SSHFP Generator
SVCB/HTTPS Builder
NAPTR Builder
LOC Builder
RP Builder
IDN Punycode Converter

DNS Utilities

DNS Record Validator
TTL Calculator
EDNS Size Estimator
DNS Label Normalizer

Zone File Tools

Zone Linter
Zone Diff
Zone Statistics
Name Length Checker

DNSSEC Tools

DNSKEY Key Tag Calculator
DS Record Generator
NSEC3 Hash Calculator
CDS/CDNSKEY Builder
RRSIG Planner

Diagnostics

DNS Diagnostics

DNS Lookup
Reverse DNS Lookup
DNS Propagation Checker
SPF Record Evaluator
DMARC Policy Checker
CAA Effective Policy
NS/SOA Consistency Check
DNSSEC AD Flag Checker
SOA Serial Analyzer

HTTP Diagnostics

HTTP Headers Analyzer
Redirect Trace
Security Headers Analyzer
CORS Policy Checker
HTTP Performance Analyzer

TLS Diagnostics

TLS Certificate Analyzer
TLS Versions Probe
TLS ALPN Negotiation

Network Diagnostics

TCP Port Checker
HTTP Ping

Email Diagnostics

MX Health Checker
SPF Policy Checker
DMARC Policy Checker

RDAP Diagnostics

Domain RDAP Lookup
IP Address RDAP Lookup
ASN RDAP Lookup

Reference

Fundamentals

CIDR Notation Explained
VLSM in Plain English
Route Summarization / Supernetting

IPv6 Addressing

IPv6 Address Types & Key Prefixes
Common IPv6 Prefix Lengths
IPv4 in IPv6
IPv6 Privacy Addresses

Special Addresses

Common Subnet Sizes
Network Classes (A/B/C)
Reserved IP Ranges
Special-Use IPv4 Blocks (RFC 6890)
Private vs Public IP Addresses
Carrier-Grade NAT Explained
Link-Local & APIPA Addresses
IPv4 & IPv6 Multicast Basics

DNS & Protocols

Reverse DNS (PTR Records)
Reverse Zones for CIDR Delegation
ICMP & ICMPv6: Common Types
ARP vs NDP

Network Operations

What is an ASN?
Common TCP/UDP Ports
ACL Wildcard Masks
Common MTU/MSS Values

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Networking Toolbox is licensed under MIT © Alicia Sykes 2025

API

Yes, we have an API! It's free to use, doesn't require an API key nor CORS.

Networking Toolbox is licensed under MIT, (C) Alicia Sykes 2025

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