go
poezje.com.pl use this as a mailserver. expressweb.pl is delegated to two nameservers, however both delegated nameservers are missing in the zone and two other nameservers are listed instead. There are two duplicated IP numbers. Some of them are on the same IP network. Incoming mail for expressweb.pl is handled by one mailserver at netcentrica.pl. expressweb.pl has one IP number.

expressweb.pl
a records
 
+ 79.133.193.91 79.133.192.0/19 AS20853  
+ ---  
ns-soa records
ns1.expressweb.pl
+ 79.133.193.91 79.133.192.0/19 AS20853  
+ ---  
ns records
ns1.expressweb.pl
+ 79.133.193.91 79.133.192.0/19 AS20853  
+ ---  
ns2.expressweb.pl
+ 79.133.193.92 79.133.192.0/19 AS20853 ip-79-133-193-92.netcentrica.pl
+ --- ip-79-133-193-92.netcentrica.pl
ns1.netcentrica.pl
+ 79.133.193.91 79.133.192.0/19 AS20853  
+ ---  
ns2.netcentrica.pl
+ 79.133.193.92 79.133.192.0/19 AS20853 ip-79-133-193-92.netcentrica.pl
+ --- ip-79-133-193-92.netcentrica.pl
mx records
s7.netcentrica.pl
+ 79.133.193.91 79.133.192.0/19 AS20853  
+ ---  
domains using this as mailserver
poezje.com.pl
nameservers missing in parent delegation
ns1.expressweb.pl
ns2.expressweb.pl
nameservers missing in zone
ns1.netcentrica.pl
ns2.netcentrica.pl