Is your site IPv6 ready?

Hostname comcast.net does have IPv6-addressed nameservers defined.

Hostname top-level domain (net.) does have IPv6-addressed nameservers defined.

Hostname comcast.net does have an IPv4 A record (96.99.227.0).

Hostname does not have IPv6 AAAA record.

Hostname comcast.net does not have an MX with an AAAA record.

IPv6-accessible nameservers at top-level domain (2001:500:856e::30, 2001:500:d937::30, 2001:501:b1f9::30, 2001:502:1ca1::30, 2001:502:7094::30, 2001:502:8cc::30, 2001:503:231d::2:30, 2001:503:39c1::30, 2001:503:83eb::30, 2001:503:a83e::2:30, 2001:503:d2d::30, 2001:503:d414::30, 2001:503:eea3::30) do provide glue pointing to v6-accessible nameservers for comcast.net (2001:558:1004:7:68:87:85:132, 2001:558:100a:5:68:87:68:244, 2001:558:100e:5:68:87:72:244, 2001:558:1014:c:68:87:76:228, 2001:558:fe23:8:69:252:250:103).

Successfully connected to comcast.net on port 80 over IPv4.

Could not connect to comcast.net on port 80 over IPv6.

Could not establish connection to URL http://comcast.net.