Yes — upenn.edu has IPv6.

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

This is a saved measurement from 2026-11-02 16:56 UTC. Check upenn.edu live now

IPv6 readiness

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

Website over IPv6 upenn.edu has 2 IPv6 addresses and answers on every one we tested. ✓ 2620:12a:8001::4 answers · 443✓ 2620:12a:8000::4 answers · 443	yes
www over IPv6 www.upenn.edu has 2 IPv6 addresses and answers on every one we tested. ✓ 2620:12a:8000::4 answers · 443✓ 2620:12a:8001::4 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mxa-00390e01.gslb.pphosted.com ✗mxb-00390e01.gslb.pphosted.com ✗	no
Nameservers have IPv6 6 of 8 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. dns1.udel.edu ✗dns2.udel.edu ✗adns1.nnn.upenn.edu ✓adns2.nnn.upenn.edu ✓adns3.nnn.upenn.edu ✓adns4.upenn.edu ✓adns5.upenn.edu ✓adns6.upenn.edu ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate after 1 redirect: HTTP 200.

https://upenn.edu/ via 2620:12a:8001::4 → 301https://www.upenn.edu/ via 2620:12a:8000::4 → 200

works

What's keeping upenn.edu from an A

Mail servers without IPv6
mxa-00390e01.gslb.pphosted.com, mxb-00390e01.gslb.pphosted.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

upenn.edu Has IPv6

A (IPv4)	23.185.0.4
AAAA (IPv6)	2620:12a:8001::4 2620:12a:8000::4

www.upenn.edu Has IPv6

A (IPv4)	23.185.0.4
AAAA (IPv6)	2620:12a:8000::4 2620:12a:8001::4

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: upenn.edu
Measured 2026-11-02 16:56:29 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    23.185.0.4
AAAA (IPv6): 2620:12a:8001::4, 2620:12a:8000::4
www AAAA:    2620:12a:8000::4, 2620:12a:8001::4

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: upenn.edu has 2 IPv6 addresses and answers on every one we tested.
    2620:12a:8001::4: answers (TCP 443)
    2620:12a:8000::4: answers (TCP 443)
- www over IPv6: www.upenn.edu has 2 IPv6 addresses and answers on every one we tested.
    2620:12a:8000::4: answers (TCP 443)
    2620:12a:8001::4: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers has an AAAA record.
- Nameservers have IPv6: 6 of 8 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 200.
    https://upenn.edu/ via 2620:12a:8001::4 -> HTTP 301, certificate: valid
    https://www.upenn.edu/ via 2620:12a:8000::4 -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/1VlLidWazD

Permanent link: aaaa.bot/r/1VlLidWazD · How we measure

Checked 2026-11-02 16:56:29 UTC. Full DNS report: dns.pizza/domain/upenn.edu · Age, certificate and blocklists: how.is/upenn.edu · JSON: /api/v1/upenn.edu