Yes — comcast.net 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 comcast.net has an AAAA record and answers on it. ✓ 2001:558:feed:dc:96:99:240:167 answers · 443	yes
www over IPv6 www.comcast.net has 2 IPv6 addresses and answers on every one we tested. ✓ 2600:1408:c400:f97::1b62 answers · 443✓ 2600:1408:c400:f80::1b62 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mx1.mxge.comcast.net ✗mx2.mxge.comcast.net ✗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 2 redirects: HTTP 403.

https://comcast.net/ via 2001:558:feed:dc:96:99:240:167 → 302https://www.comcast.net/ via 2600:1408:c400:f97::1b62 → 301https://www.xfinity.com/ via 2600:1408:c400:188d::2af2 → 403

works

What's keeping comcast.net from an A

Mail servers without IPv6
mx1.mxge.comcast.net, mx2.mxge.comcast.net, 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

comcast.net Has IPv6

A (IPv4)	96.99.240.167
AAAA (IPv6)	2001:558:feed:dc:96:99:240:167

www.comcast.net Has IPv6

Alias of	www.comcast.net.edgekey.net → e7010.dscg.akamaiedge.net
A (IPv4)	104.86.166.187
AAAA (IPv6)	2600:1408:c400:f97::1b62 2600:1408:c400:f80::1b62

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: comcast.net
Measured 2026-10-30 22:09:04 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    96.99.240.167
AAAA (IPv6): 2001:558:feed:dc:96:99:240:167
www AAAA:    2600:1408:c400:f97::1b62, 2600:1408:c400:f80::1b62

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: comcast.net has an AAAA record and answers on it.
    2001:558:feed:dc:96:99:240:167: answers (TCP 443)
- www over IPv6: www.comcast.net has 2 IPv6 addresses and answers on every one we tested.
    2600:1408:c400:f97::1b62: answers (TCP 443)
    2600:1408:c400:f80::1b62: 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 2 redirects: HTTP 403.
    https://comcast.net/ via 2001:558:feed:dc:96:99:240:167 -> HTTP 302, certificate: valid
    https://www.comcast.net/ via 2600:1408:c400:f97::1b62 -> HTTP 301, certificate: valid
    https://www.xfinity.com/ via 2600:1408:c400:188d::2af2 -> HTTP 403, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/TRONS-dZuo

Permanent link: aaaa.bot/r/TRONS-dZuo · How we measure

Checked 2026-10-30 22:09:04 UTC. Full DNS report: dns.pizza/domain/comcast.net · JSON: /api/v1/comcast.net