ftp.ucsd.edu 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
ftp.ucsd.edu has an AAAA record, but nothing answered on ports 443 or 80. IPv6 visitors wait for a timeout before falling back to IPv4.
✗ 2607:f720:300:202::12 no answer
broken
Mail servers (MX) have IPv6
No MX records, so mail goes to the domain's own address (implicit MX). It has an AAAA record.		yes
Nameservers have IPv6
2 of 3 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
ns-auth1.ucsd.edu ✗ns-auth3.ucsd.edu ✓ns-auth2.ucsd.edu ✓
yes
 Load ftp.ucsd.edu over IPv6 from up to six other places — a second opinion.

What's keeping ftp.ucsd.edu from an A

  1. Fix or remove the AAAA record for ftp.ucsd.edu
    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.

Check again

ftp.ucsd.edu  Has IPv6

Alias ofmirror.ucsd.edu
A (IPv4)132.239.1.12
AAAA (IPv6)2607:f720:300:202::12

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/lhUdJvdYEw · How we measure

Checked 2026-10-31 14:04:52 UTC. Full DNS report: dns.pizza/domain/ftp.ucsd.edu · JSON: /api/v1/ftp.ucsd.edu