Yes — xfinity.com has IPv6.

Has both IPv4 (A) and IPv6 (AAAA) addresses.

IPv6 readiness

Works over IPv6, with one gap: its mail servers lack IPv6.

Website over IPv6 xfinity.com has an AAAA record and answers on it. ✓ 2001:558:feed:dc:96:99:240:155 answers · 443	yes
www over IPv6 www.xfinity.com has 4 IPv6 addresses and answers on every one we tested. ✓ 2600:1408:c400:1883::2af2 answers · 443✓ 2600:1408:c400:1889::2af2 answers · 443✓ 2600:1408:c400:1886::2af2 answers · 443✓ 2600:1408:c400:1882::2af2 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mx1a1.comcast.net ✗mx1c1.comcast.net ✗mx1h1.comcast.net ✗mx2a1.comcast.net ✗mx2c1.comcast.net ✗mx2h1.comcast.net ✗	no
Nameservers have IPv6 5 of 5 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. dns101.comcast.net ✓dns102.comcast.net ✓dns103.comcast.net ✓dns104.comcast.net ✓dns105.comcast.net ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate after 1 redirect: HTTP 403.

https://xfinity.com/ via 2001:558:feed:dc:96:99:240:155 → 301https://www.xfinity.com/ via 2600:1408:c400:1883::2af2 → 403

works

What's keeping xfinity.com from an A

Mail servers without IPv6
mx1a1.comcast.net, mx1c1.comcast.net, mx1h1.comcast.net, mx2a1.comcast.net, mx2c1.comcast.net, mx2h1.comcast.net have no AAAA record, so mail from IPv6-only servers can't reach them directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

xfinity.com Has IPv6

A (IPv4)	96.99.240.155
AAAA (IPv6)	2001:558:feed:dc:96:99:240:155

www.xfinity.com Has IPv6

Alias of	www.xfinity.com.edgekey.net → e10994.dscx.akamaiedge.net
A (IPv4)	23.13.173.231
AAAA (IPv6)	2600:1408:c400:1883::2af2 2600:1408:c400:1889::2af2 2600:1408:c400:1886::2af2 2600:1408:c400:1882::2af2

Browsers on dual-stack networks will usually pick IPv6 here (the "Happy Eyeballs" algorithm races both and prefers v6).

Copy the evidence — a citation-ready record of this measurement

IPv6 measurement: xfinity.com
Measured 2026-10-31 15:45:36 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    96.99.240.155
AAAA (IPv6): 2001:558:feed:dc:96:99:240:155
www AAAA:    2600:1408:c400:1883::2af2, 2600:1408:c400:1889::2af2, 2600:1408:c400:1886::2af2, 2600:1408:c400:1882::2af2

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: xfinity.com has an AAAA record and answers on it.
    2001:558:feed:dc:96:99:240:155: answers (TCP 443)
- www over IPv6: www.xfinity.com has 4 IPv6 addresses and answers on every one we tested.
    2600:1408:c400:1883::2af2: answers (TCP 443)
    2600:1408:c400:1889::2af2: answers (TCP 443)
    2600:1408:c400:1886::2af2: answers (TCP 443)
    2600:1408:c400:1882::2af2: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers has an AAAA record.
- Nameservers have IPv6: 5 of 5 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.

Reachability = a TCP connection opened on port 443 (or 80).

HTTPS over IPv6 (not graded): Loads over IPv6 with a valid certificate after 1 redirect: HTTP 403.
    https://xfinity.com/ via 2001:558:feed:dc:96:99:240:155 -> HTTP 301, certificate: valid
    https://www.xfinity.com/ via 2600:1408:c400:1883::2af2 -> HTTP 403, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/paqsA09qZM

Permanent link: aaaa.bot/r/paqsA09qZM · How we measure

Checked 2026-10-31 15:45:36 UTC. Full DNS report: dns.pizza/domain/xfinity.com · JSON: /api/v1/xfinity.com