The Common Indexing Protocol (CIP) was an attempt in the IETF working group FIND during the mid-1990s to define a protocol for exchanging index information between directory services.
In the X.500 Directory model, searches scoped near the root of the tree (e.g. at a particular country) were problematic to implement, as potentially hundreds or thousands of directory servers would need to be contacted in order to handle that query.
The indexes contained summaries or subsets of information about individuals and organizations represented in a white pages schema.
This protocol has not seen much recent deployment, as WHOIS and LDAP environments have followed separate evolution paths.
In contrast, enterprises that manage employee, customer or student identity data in an LDAP directory have looked to federation protocols for interconnection between organizations.