Server Name Indication, or SNI, is a method by which clients such as web browsers can securely designate the domain that they are attempting to access before completing the SSL handshake.
That means that custom SSL certificates can be used on a multi-tenant system like a CDN without having to consume scarce dedicated IPv4 address space, a necessity for a truly scalable secure web.
We currently offer security via our own wildcard certificate (*.ssl.hwcdn.net) and via dedicated IP with custom certs.
Highwinds' SNI support means that users can genuinely secure the traffic of their own domains in a cost effective manner and without having to rely on a shared certificate.
Over 99% of ALL SSL connections originated from environments with full SNI support, and for some of our users, SNI support represented as high as 99.98% of their connections.
For some applications, a dedicated IP with its own standalone certificate is still going to be the proper approach, but with SNI support available on all modern browsers since 2010, it covers the vast majority of use cases.