Da MSDN:
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Remarks
Use the Seek method in conjunction with the Index property if the underlying provider supports indexes on the Recordset object. Use the Supports(adSeek) method to determine whether the underlying provider supports Seek, and the Supports(adIndex) method to determine whether the provider supports indexes. (For example, the OLE DB Provider for Microsoft Jet supports Seek and Index.)
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This method is supported only with server-side cursors. Seek is not supported when the Recordset object's CursorLocation property value is adUseClient.

This method can only be used when the Recordset object has been opened with a CommandTypeEnum value of adCmdTableDirect.
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