XCON: Application Protocol Data Unit (APDU) Logs (BF0.LOG)

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Article ID: 163324 - View products that this article applies to.
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Application Protocol Data Unit (APDU) text logs are binary representations of communication among Microsoft Exchange Message Transfer Agents (MTAs) in different Sites and between MTA and client applications within a Site. The log includes the fully-encoded ASN.1 envelope. This is useful for verifying when messages from remote MTAs are bad or invalidly formatted.


Increasing Diagnostic Logging levels to Medium or higher for both the MTA's APDU and X.400 Service categories will generate BF*.LOG files in the exchsrvr\MTADATA directory. The current log is always named BF0.LOG. Prior logs are named BF#.LOG with the # increasing with the age of the log. When a log reaches 5 megabytes in size it is renamed and a new log is begun.

NOTE: There is no difference between Medium and Maximum for the APDU category. However, in addition to its influence on APDU logs, the diagnostics logging level of the X.400 Service category determines which X.400 events are written to event logs.

APDU logs can be instrumental in diagnosing problems with the MTA. However, they are valuable only to those familiar with ASCII translations of X.400 protocol. These logs can grow quite large very quickly and cause performance on the Server to suffer.

An ASN.1 Parser can be used to decode the data in a BF0.LOG.


Article ID: 163324 - Last Review: October 28, 2006 - Revision: 3.3
  • Microsoft Exchange Server 5.5 Standard Edition
  • Microsoft Exchange Server 4.0 Standard Edition
  • Microsoft Exchange Server 5.0 Standard Edition
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This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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