go
adsl.dynamic.totbb.net are subdomains to this hostname. totbb.net is delegated to two nameservers, however two extra nameservers are listed in the zone. All of them are on the same IP network. totbb.net has one IP number.

totbb.net
a records
 
+ 203.113.9.20 203.113.0.0/17 AS9737  
+ ---  
ns-soa records
ns1.totbb.net
+ 203.113.9.52 203.113.0.0/17 AS9737 -
+ --- -
ns records
ns1.totbb.net
+ 203.113.9.52 203.113.0.0/17 AS9737 -
+ --- -
ns1.totisp.net
+ 203.113.15.99 203.113.0.0/17 AS9737 -
ns2.totbb.net
+ 203.113.11.9 203.113.0.0/17 AS9737 -
ns2.totisp.net
+ 203.113.15.100 203.113.0.0/17 AS9737 -
subdomains
adsl.dynamic.totbb.net
nameservers missing in parent delegation
ns1.totisp.net
ns2.totisp.net