Incoming mail for www1.dc.sint.pl is handled by one mailserver at dc.sint.pl. www1.dc.sint.pl has one IP number , which also has a corresponding reverse pointer. n1.pl, pl.pl, a4.pl, jjw.pl, ids.pl and at least 100 other hosts share mailservers with this domain. dc.sint.pl is a domain controlled by two nameservers at sint.pl. They are on different IP networks. Incoming mail for dc.sint.pl is handled by one mailserver also at dc.sint.pl. dc.sint.pl has one IP number. www1.dc.sint.pl is hosted on a server in Poland.