uni-passau.de

dns-1.dfn.de, ns.fim.uni-passau.de, ns.forwiss.uni-passau.de, ns.rz.uni-passau.de

Found

Parent zone

de

Delegation from

a.nic.de (194.0.0.53)

NS at the parent

dns-1.dfn.de, ns.fim.uni-passau.de, ns.forwiss.uni-passau.de, ns.rz.uni-passau.de

NS in the zone

dns-1.dfn.de, ns.fim.uni-passau.de, ns.forwiss.uni-passau.de, ns.rz.uni-passau.de

Checks

• ✓ 4 nameservers #6

  Delegated to dns-1.dfn.de, ns.fim.uni-passau.de, ns.forwiss.uni-passau.de, ns.rz.uni-passau.de.
• ✓ Parent and zone agree #7

  The parent delegation and the zone's NS records list the same nameservers.
• !

  Glue differs from the zone

  The addresses at the parent (glue) differ from the addresses in the zone: ns.forwiss.uni-passau.de (glue 132.231.20.100, zone 132.231.20.100, 2001:638:a07:a:1::100). Update the glue at your registrar.

  #8
• ✓ All names resolve #9

  Every nameserver name has an address and is not an alias.
• ✓ Nameservers in different networks #10

  The nameservers are spread over 4 IPv4 /24s and 2 IPv6 /48s.
• i

  All nameservers in one AS

  All nameserver addresses are announced by one network operator (AS680 (DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE): 6 addresses). An outage or attack on that network affects all nameservers; large anycast providers mitigate this, but a secondary DNS provider adds independence.

  #11
• i

  All nameserver names under .de

  All nameserver names are under one TLD, so a problem with that TLD also makes the nameservers unreachable. Some operators use names under two TLDs for extra resilience.

  #12
• i

  Partly IPv6

  These nameservers have no IPv6 address: ns.fim.uni-passau.de, ns.rz.uni-passau.de.

  #13

6 of 6 addresses answer authoritatively

Found

Checks

• ✓ All respond #14

  All 6 nameserver addresses answered.
• ✓ All authoritative #15

  Every responding nameserver answers authoritatively for the zone.
• ✓ No recursion #16

  The nameservers do not answer recursive queries for other domains.
• !

  Software version disclosed

  These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns.forwiss.uni-passau.de: "9.18.49-1~deb12u2-Debian". Hide or replace the version string.

  #17
• ✓ Zone transfers refused #18

  No nameserver allows a zone transfer to the public.
• ✓ TCP supported #19

  All nameservers answer over TCP.
• ✓ EDNS supported #20

  All nameservers support EDNS(0).
• ✓ Public addresses #21

  All nameserver addresses are publicly routable.

serial 2026102675 · primary ns.rz.uni-passau.de

Found

Primary (MNAME)

ns.rz.uni-passau.de

Contact (RNAME)

postmaster.ns.rz.uni-passau.de

Serial

2026102675

Refresh / retry

21600 s / 3600 s

Expire

604800 s

Negative TTL

86400 s

Serial per nameserver

Checks

• ✓ Serial 2026102675 everywhere #22

  All nameservers serve the same version of the zone.
• ✓ Timers within recommendations #23

  SOA refresh 6h, retry 1h, expire 7d, negative TTL 1d.
• ✓ Primary is a public nameserver #24

  The primary nameserver ns.rz.uni-passau.de is one of the listed nameservers.
• ✓ Contact postmaster@ns.rz.uni-passau.de #25

  The SOA RNAME postmaster.ns.rz.uni-passau.de means postmaster@ns.rz.uni-passau.de.
• !

  Serial date in the future

  The serial 2026102675 looks like a date (YYYYMMDDnn) in the future (2026-10-26). It can only grow, so a wrong date can't be undone without a serial wrap-around.

  #26