Yes — sophos.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 sophos.com has 2 IPv6 addresses and answers on every one we tested. ✓ 2600:1408:5400:35::17ca:e6e4 answers · 443✓ 2600:1408:5400:35::17ca:e6d0 answers · 443	yes
www over IPv6 www.sophos.com has 2 IPv6 addresses and answers on every one we tested. ✓ 2600:1408:c400:16::17d4:f81a answers · 443✓ 2600:1408:c400:16::17d4:f812 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mx-01-eu-west-1.prod.hydra.sophos.com ✗mx-02-eu-west-1.prod.hydra.sophos.com ✗	no
Nameservers have IPv6 6 of 6 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. a11-66.akam.net ✓a1-100.akam.net ✓a9-65.akam.net ✓a10-65.akam.net ✓a14-67.akam.net ✓a18-64.akam.net ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate after 3 redirects: HTTP 200.

https://sophos.com/ via 2600:1408:5400:35::17ca:e6e4 → 301https://www.sophos.com/ via 2600:1408:c400:16::17d4:f81a → 302https://www.sophos.com/en-us/// via 2600:1408:c400:16::17d4:f81a → 308https://www.sophos.com/en-us via 2600:1408:c400:16::17d4:f81a → 200

works

What's keeping sophos.com from an A

Mail servers without IPv6
mx-01-eu-west-1.prod.hydra.sophos.com, mx-02-eu-west-1.prod.hydra.sophos.com 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

sophos.com Has IPv6

A (IPv4)	23.212.251.136 23.212.251.150
AAAA (IPv6)	2600:1408:5400:35::17ca:e6e4 2600:1408:5400:35::17ca:e6d0

www.sophos.com Has IPv6

A (IPv4)	23.205.106.26 23.205.106.22
AAAA (IPv6)	2600:1408:c400:16::17d4:f81a 2600:1408:c400:16::17d4:f812

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: sophos.com
Measured 2026-10-31 01:04:35 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    23.212.251.136, 23.212.251.150
AAAA (IPv6): 2600:1408:5400:35::17ca:e6e4, 2600:1408:5400:35::17ca:e6d0
www AAAA:    2600:1408:c400:16::17d4:f81a, 2600:1408:c400:16::17d4:f812

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: sophos.com has 2 IPv6 addresses and answers on every one we tested.
    2600:1408:5400:35::17ca:e6e4: answers (TCP 443)
    2600:1408:5400:35::17ca:e6d0: answers (TCP 443)
- www over IPv6: www.sophos.com has 2 IPv6 addresses and answers on every one we tested.
    2600:1408:c400:16::17d4:f81a: answers (TCP 443)
    2600:1408:c400:16::17d4:f812: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers has an AAAA record.
- Nameservers have IPv6: 6 of 6 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 3 redirects: HTTP 200.
    https://sophos.com/ via 2600:1408:5400:35::17ca:e6e4 -> HTTP 301, certificate: valid
    https://www.sophos.com/ via 2600:1408:c400:16::17d4:f81a -> HTTP 302, certificate: valid
    https://www.sophos.com/en-us/// via 2600:1408:c400:16::17d4:f81a -> HTTP 308, certificate: valid
    https://www.sophos.com/en-us via 2600:1408:c400:16::17d4:f81a -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/NwXoo3raG3

Permanent link: aaaa.bot/r/NwXoo3raG3 · How we measure

Checked 2026-10-31 01:04:35 UTC — one of the top 1,000 sites, re-checked weekly. Re-check now. Full DNS report: dns.pizza/domain/sophos.com · JSON: /api/v1/sophos.com