简介：SeveralyearsagoDESYfacedtheneedtochangetheElectronicMailservicetosupportitonacentralclusterofservers.ThecentralizedarchitecturewasnecessaryfordeploymentofunifiedinternalE-Mailstandards,betterqualityofserviceandsecurity,ToimplemnetanewpolicyforElectronicMailServiceandavoidhugemodificationstoafewhundredsnetworknodes,anadditionalDNSfeaturehasbeenaddedtoISC's(InternetSoftwareConsortium)softwarebind-4.9.7.TheDNSserversrunningatDESYarecapableofdistingushingbetweenDNSqueriescomingfrominsideandoutsideofthecampusnetwokrandreplywithdifferentlistofMX(MailExchanger)records.TheexternalhostsalwaysgetalistofMXrecordspointingtothecentralmailserverswhiletheinternalhostsmayusedifferentpathsformailexchangewithinthecampusnetwork.AmodifiedversionofDNSsoftwarehasbeenusedatDESYsince1997,Itisfullycompliantwiththeoriginalgoaloftheprojcetandshowsgoodoperationalperformanceandreliability.