About Knowledge References98 Red Hat Directory Server Deployment Guide • May 2005The referral tells the client application to contact the host europe.example.comon port 389 and submit a search rooted atou=people,l=europe,dc=example,dc=com.The LDAP client application you use determines how a referral is handled. Someclient applications automatically retry the operation on the server to which theyhave been referred. Other client applications simply return the referralinformation to the user. Most LDAP client applications provided by Red HatDirectory Server (such as the command-line utilities or the Directory ServerGateway) automatically follow the referral. The same bind credentials you supplyon the initial directory request are used to access the server.Most client applications follow a limited number of referrals, or hops. The limit onthe number of referrals followed reduces the time a client application spendstrying to complete a directory lookup request and helps eliminate hung processescaused by circular referral patterns.About Default ReferralsDefault referrals are returned to clients when the server or database contacteddoes not contain the data requested.Directory Server determines whether a default referral should be returned bycomparing the DN of the requested directory object against the directory suffixessupported by the local server. If the DN does not match the supported suffixes,the Directory Server returns a default referral.For example, a directory client requests the following directory entry:uid=bjensen,ou=people,dc=example,dc=comHowever, the server manages only entries stored under thedc=europe,dc=example,dc=com suffix. The directory returns a referral to theclient that indicates which server to contact for entries stored in thedc=example,dc=com suffix. The client then contacts the appropriate server andresubmits the original request.You configure the default referral to point to a Directory Server that has moreknowledge about the distribution of your directory. Default referrals for theserver are set by the nsslapd-referral attribute. Default referrals for eachdatabase in your directory installation are set by the nsslapd-referral attributein the database entry in the configuration. These attribute values are stored in thedse.ldif file.For information on configuring default referrals, see the Red Hat Directory ServerAdministrator’s Guide.
