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Networking Toolbox
The sysadmin's Swiss Army knife
Subnetting
CIDR
IP Tools
DNS Tools
Lookups
Ref
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
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Alicia Sykes
2025
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