IPv4 vs. IPv6

IPv4 and IPv6 are two versions of the Internet Protocol. Both move packets between networks, but they use different address sizes and notation. Many modern devices and websites support both at the same time.

IPv4 format

An IPv4 address contains 32 bits. It is normally written as four decimal octets, for example 203.0.113.25. A 32-bit space contains about 4.3 billion possible values, although many ranges are reserved for private networks, testing, multicast, and other special purposes.

IPv6 format

An IPv6 address contains 128 bits and is written as eight groups of hexadecimal digits. Consecutive groups of zeros can be compressed once with a double colon. For example, 2001:0db8:0000:0000:0000:0000:0000:0025 can be written as 2001:db8::25.

DNS record differences

DNS uses an A record to publish an IPv4 address and an AAAA record to publish an IPv6 address. A website may return one type, both types, or several addresses for load balancing and redundancy.

Does IPv6 make a site faster?

Not automatically. Performance depends on routing, provider support, network quality, server placement, and software configuration. A well-routed IPv6 path may perform better than IPv4, but a poor path may perform worse. Modern operating systems test available paths and generally prefer the one expected to work best.

Security differences

Neither version is automatically secure simply because of its address format. Firewalls, access controls, encryption, patching, authentication, and monitoring remain necessary. IPv6 can reduce dependence on address translation, but publicly reachable addressing does not mean every device should be openly accessible.

Which should a website support?

Website owners should normally keep reliable IPv4 service while adding IPv6 when their hosting and monitoring support it. Test both A and AAAA records, TLS certificates, firewalls, origin access, and application logs before announcing full dual-stack support.

Check a domain’s IPv4 and IPv6 records