IP fundamentals
IPv4 vs IPv6: Differences and Dual-Stack Checks
Learn about IPv4 and IPv6 address formats, dual-stack connections, and VPN routing, including why one device can use different exits.
Address format and space
IPv4 uses 32-bit addresses, normally written as four decimal groups. IPv6 uses 128-bit addresses, written in colon-separated hexadecimal with rules for compressing zero groups. Both provide network addressing. Seeing an IPv6 address does not tell you that a VPN is active or that the connection is anonymous.
One device can use both protocols
A dual-stack device can choose IPv4 or IPv6 depending on the destination and connection conditions. Two websites may therefore show different versions. An ISP’s IPv4 path might use shared address translation while IPv6 follows a separate route. Browser proxy coverage can also vary, making separate path checks useful.
Check a VPN’s dual-stack behavior
Record both exits before enabling your VPN, then repeat the exit-path check. Review whether the VPN supports or blocks IPv6. If IPv4 changes while IPv6 still uses the original provider, compare that behavior with your intended split-tunnel settings. Different address strings alone are not proof of a leak; IPv4 and IPv6 cannot be the same address string.
Interpret unavailable results
A failed probe may reflect the destination, network rules, or browser restrictions. A single failure does not establish that the entire device lacks protocol support. Retry on another connection and compare the result with the operating system’s network information.