de to rwth-aachen.de: No valid RRSIGs made by a key corresponding to a DS RR were found covering the DNSKEY RRset, resulting in no secure entry point (SEP) into the zone. See RFC 4035, Sec. 2.2, RFC 6840, Sec. 5.11. (134.130.4.9, 134.130.5.9, 193.174.75.50, 193.174.75.54, 2001:638:d:b101::1, 2001:638:d:b102::1, 2a00:8a60:0:4::9, 2a00:8a60:0:5::9, TCP_-_EDNS0_4096_D_KN, UDP_-_EDNS0_4096_D_KN)
de to rwth-aachen.de: The DS RRset for the zone included algorithm 8 (RSASHA256), but no DS RR matched a DNSKEY with algorithm 8 that signs the zone's DNSKEY RRset. See RFC 4035, Sec. 2.2, RFC 6840, Sec. 5.11. (134.130.4.9, 134.130.5.9, 193.174.75.50, 193.174.75.54, 2001:638:d:b101::1, 2001:638:d:b102::1, 2a00:8a60:0:4::9, 2a00:8a60:0:5::9, TCP_-_EDNS0_4096_D_KN, UDP_-_EDNS0_4096_D_KN)
rwth-aachen.de zone: The server(s) were not responsive to queries over TCP. See RFC 1035, Sec. 4.2. (134.130.4.9, 2a00:8a60:0:5::9)
rwth-aachen.de/SOA: No response was received from the server over TCP (tried 3 times). See RFC 1035, Sec. 4.2. (134.130.4.9, 2a00:8a60:0:5::9, TCP_-_EDNS0_4096_D_N)
Warnings (5)
./DNSKEY: The server appears to support DNS cookies but did not return a COOKIE option. See RFC 7873, Sec. 5.2.3. (2001:500:2f::f, UDP_-_EDNS0_512_D_KN)
rwu4n.obsge.rwth-aachen.de/A has warnings; select the "Denial of existence" DNSSEC option to see them.
rwth-aachen.de/CDNSKEY has warnings; select the "Denial of existence" DNSSEC option to see them.
rwth-aachen.de/CDS has warnings; select the "Denial of existence" DNSSEC option to see them.
rwth-aachen.de/CNAME has warnings; select the "Denial of existence" DNSSEC option to see them.