cz to vlada.cz: Authoritative AAAA records exist for ns1.cdt.cz, but there are no corresponding AAAA glue records. See RFC 1034, Sec. 4.2.2.
vlada.cz/MX: No response was received until the UDP payload size was decreased, indicating that the server might be attempting to send a payload that exceeds the path maximum transmission unit (PMTU) size. See RFC 6891, Sec. 6.2.6. (2001:1a48:2b::d42f:176e, 2001:1a48:2b::d42f:1773, UDP_-_EDNS0_4096_D_KN)