IPv4 and IPv6 are the two main versions of internet protocol (IP) used to transmit data over the internet. IPv4 addresses are 32-bit numbers typically written in dotted-decimal notation, such as 192.168.1.1. IPv6 addresses, on the other hand, are 128-bit numbers written in hexadecimal notation, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
As the number of internet-connected devices has grown, the number of available IPv4 addresses has become increasingly scarce. To address this issue, IPv6 was developed to provide a much larger pool of addresses. Many organizations are now moving to IPv6 to take advantage of its expanded address space, but IPv4 is still widely used and is likely to be in use for some time to come.
Because both IPv4 and IPv6 are still in use, it's important for a protective DNS feature to support both address versions.
This is known as dual-stack support and Securd is a dual-stack solution. Without dual-stack support, an organization's protective DNS feature would only be able to block malicious activity from one address version, leaving the other vulnerable. This is particularly important for Windows endpoints, as Windows supports both IPv4 and IPv6 by default. In order for a protective DNS feature to be effective on Windows endpoints, it must be able to resolve and block malicious activity from both IPv4 and IPv6 addresses.