Administrative Limits Governing Active Directory and ADAM

In Chapter 4, in the section titled Returning Many Results with Paged Searches, we briefly mentioned an LDAP query policy called MaxPageSize. As it turns out, MaxPageSize is just one of many policies enforced by Active Directory and ADAM that can affect the behavior of our searches. Since the server enforces these policies, they always override any settings requested by the client when sending a search request.

As such, it is important for developers to know which settings will have an impact on their code. Table 5.1 summarizes the limits.

Table 5.1. Administrative Limits for LDAP Searches with Active Directory

Value	Description	Default
InitRecvTimeout	Initial Receive Timeout. This is the amount of time a server will wait for the client to send the initial request after receiving a new connection.	120 seconds
MaxConnections	Maximum open connections allowed. Any connections after this limit mean that another connection will be dropped.	5,000 connections
MaxConnIdleTime	Maximum amount of time an open connection can be idle before disconnection.	900 seconds
MaxActiveQueries	Maximum number of queries that will execute at one time. If this limit is reached, subsequent queries will receive a "busy" notification error.	20 queries
MaxNotification-PerConnection	Maximum number of notifications a client can request per connection. Client will receive a "busy" error when this limit is exceeded.	5 notifications
MaxPageSize	Maximum number of results returned per page. If the number of selected results exceeds this value, only this limit is returned, unless paging is performed. If paging is used, this limit is enforced per page.	1,000 results
MaxQueryDuration	Maximum length of time a query can execute. If this limit is exceeded, a timeLimitExceeded error will be raised. To exceed this limit, paging must be used, but then this limit is enforced per page as well.	120 seconds
MaxTempTableSize	Maximum size of temporary storage allocated for queries. This storage is used to sort and select intermediate results. A size smaller than the expected result set will result in decreased performance.	10,000 results
MaxResultSetSize	Maximum size of the intermediate data stored in a paged search. The server might store this intermediate data between pages in a paged search to speed subsequent pages. When this value is exceeded, the server will discard older data.	262,144 bytes
MaxPoolThreads	Maximum number of threads created for query execution and listening for network input/output. This is a per-processor value.	4 per CPU
MaxDatagramRecv	Maximum size of a datagram that can be processed. Datagram requests larger than this limit will be discarded.	1,024 bytes