Technical Comparison · Reviewed 1 November 2026 · Primary Sources: IETF RFC 791, RFC 8200, RFC 5952
IPv4 vs IPv6: Address Format, Architecture & Practical Differences
A technical comparison of 32-bit IPv4 and 128-bit IPv6 packet headers, address notation, subnetting conventions, NAT requirements, and dual-stack routing.
| Specification | IPv4 (RFC 791, 1981) | IPv6 (RFC 8200, 1998/2017) |
|---|---|---|
| Address Width | 32 bits (4 bytes) | 128 bits (16 bytes) |
| Total Address Space | 2³² = 4,294,967,296 (~4.29 × 10⁹) | 2¹²⁸ ≈ 3.40 × 10³⁸ addresses |
| Text Notation | Dotted-decimal (49.44.0.1) | 8 hex hextets (2405:200:1601::1) |
| Base Header Size | Variable 20–60 bytes (includes header checksum) | Fixed 40 bytes (no header checksum; extension headers) |
| Broadcast Traffic | Uses directed and limited broadcast | No broadcast; replaced by scoped multicast (ff00::/8) |
| Address Configuration | Manual or stateful DHCPv4 | SLAAC (RFC 4862) + Router Advertisements or DHCPv6 |
| DNS Record Type | A (Type 1) & in-addr.arpa | AAAA (Type 28) & ip6.arpa |
1. Why IPv4 Cannot Directly Talk to IPv6 Without Dual-Stack or Translation
IPv4 and IPv6 are separate network-layer protocols with different packet header layouts. An IPv4-only host cannot send raw packets directly to an IPv6-only host. To maintain seamless connectivity across the internet, networks rely on Dual-Stack operation (RFC 4213)—running both IPv4 and IPv6 simultaneously—or translation mechanisms such as NAT64/DNS64 (RFC 6146) and 464XLAT (RFC 6877), which are widely deployed on Indian 4G/5G mobile networks.
2. Common Misconceptions About Speed and Security
Neither IPv4 nor IPv6 is inherently "more secure" simply because of its address length. While IPv6 eliminates the need for Carrier-Grade NAT (CGNAT) by giving every subscriber a global /64 prefix, modern home routers still run a stateful IPv6 firewall that blocks unsolicited inbound connections by default. In terms of latency, IPv6 can slightly outperform CGNAT IPv4 on Indian mobile networks because packets bypass carrier NAT translation boxes.
Test your own connection right now using our IPv4 Connectivity Checker, IPv6 Connectivity Checker, or convert addresses between formats in the IP Address Converter.
Technical Specifications & Protocol Facts
Authoritative parameters, dimensions, and IETF RFC compliance
| Parameter / Dimension | Technical Specification | Standard / Authority |
|---|---|---|
| Canonical Document Scope | IPv4 vs IPv6 — Route /ipv4-vs-ipv6 | IPAddressLookup.in Technical Reference |
| Supported Address Families | IPv4 (32-bit dotted-decimal) & IPv6 (128-bit hexadecimal) | RFC 791 / RFC 8200 / RFC 5952 |
| Authoritative Registration Protocol | Registration Data Access Protocol (RDAP) via IANA Bootstrap | RFC 7480–7484 / RFC 9224 |
| Special-Purpose Range Classification | Private LAN (RFC 1918), Shared CGNAT 100.64.0.0/10 (RFC 6598), ULA (RFC 4193) | RFC 6890 IANA Registry |
Frequently Asked Questions
Concise answers verified against IANA, APNIC, and IETF protocol standards
What is the primary purpose of IPv4 vs IPv6?
Technical comparison of 32-bit dotted-decimal IPv4 and 128-bit hexadecimal IPv6 packet addressing. Every output on IPAddressLookup.in follows IETF RFC standards and cites primary RIR/IANA sources.
Are IP and network queries on this page logged or shared with advertisers?
No. IPAddressLookup.in operates on a strict data-minimization model with stateless query execution, short-lived caching (15 minutes max for upstream RDAP/DNS), and zero persistent user lookup history.
How often is the technical documentation on IPAddressLookup.in reviewed?
All protocol calculators, RFC citations, and Indian telecom notes are verified by the 2026-11-01 editorial and engineering review cycle.
Related Network Tools & Technical Guides
Contextual utilities and reference documentation verified for this workflow
Diagnostic & Calculation Utilities
- IPv4 Checker
Inspect the visitor IPv4 address observed by the server, octet breakdown, and RFC 1918 / RFC 6598 CGNAT status.
- IPv6 Checker
Inspect 128-bit IPv6 reachability, eight-hextet structure, compressed/expanded form, and Indian dual-stack context.
- IP Address Converter
Convert IPv4 and IPv6 addresses across canonical, expanded, decimal integer, hexadecimal, binary, and reverse ARPA forms.
- Subnet Calculator
Calculate network address, broadcast, usable host range, wildcard mask, and 32-bit binary mask for /0 to /32.
IPv4 vs IPv6 · Canonical: https://ipaddresslookup.in/ipv4-vs-ipv6 · Reviewed: 2026-11-01
Reviewer: IPAddressLookup.in Technical Network Utility Group · Stateless Privacy · Accuracy & Data Limits