smtp.univ-paris-diderot.fr publishes IPv6 but doesn't answer on it.

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

F
IPv6 readiness
Publishes IPv6 but doesn't answer on it — worse than having none.
Website over IPv6
smtp.univ-paris-diderot.fr has an AAAA record, but nothing answered on ports 443 or 80. IPv6 visitors wait for a timeout before falling back to IPv4.
✗ 2001:660:3301:8000::1:2 no answer✗ 2001:660:3301:8000::1:1 no answer
broken
Mail servers (MX) have IPv6
At least one mail server has no AAAA record (2 of 3 checked do).
potemkin.univ-paris7.fr ✓shiva.jussieu.fr ✗korolev.univ-paris7.fr ✓
partly
Nameservers have IPv6
2 of 3 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
korolev.univ-paris7.fr ✓shiva.jussieu.fr ✗potemkin.univ-paris7.fr ✓
yes
 Load smtp.univ-paris-diderot.fr over IPv6 from up to six other places — a second opinion.

What's keeping smtp.univ-paris-diderot.fr from an A

  1. Fix or remove the AAAA record for smtp.univ-paris-diderot.fr
    Something published an IPv6 address but nothing answers on it, so IPv6 visitors wait for a timeout first. Either make the server listen on IPv6 (and allow ports 443/80 through its firewall), or delete the AAAA record until it does.
  2. Mail servers without IPv6
    shiva.jussieu.fr has no AAAA record, so mail from IPv6-only servers can't reach it directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

smtp.univ-paris-diderot.fr  Has IPv6

Alias ofrelay.univ-paris7.fr
A (IPv4)194.254.61.141
194.254.61.138
AAAA (IPv6)2001:660:3301:8000::1:2
2001:660:3301:8000::1:1

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

 Permanent link: aaaa.bot/r/kAGl0vQwC8 · How we measure

Checked 2026-11-01 01:02:04 UTC. Full DNS report: dns.pizza/domain/smtp.univ-paris-diderot.fr · JSON: /api/v1/smtp.univ-paris-diderot.fr