DSAccess implements a directory access cache that stores
recently accessed information for a configurable length of
time. This reduces the number of queries made to global
catalog servers
Starting with Exchange Server 2000 Microsoft began using
the AD - Active Directory as the repository for Exchange
related data. So microsoft had to create certain rules to
make sure that the Exchange Server communiated with the AD
in such a way that it did not create excessive network
traffic or overwhelm domain controllers with too many LDAP
requests. ( For beginners i would like to explain this in a
little more detail - whenever Exchange would need any data
from the Active Directory it will use an LDAP query for
geting the data. Now all the data is present in the AD and
AD is present on DCs - that is Domain Controlers, hence
Exchange would be sending LDAP queries to DCs for the data.)
So for controlling the communication between
Exchange and AD; microsoft created a component called the
DS Access. DS Access would act as an intermediary between
the AD and Exchange Server.
Thus, DS is used by all the Exchange components
to query the AD and acquire the configuration and recipient
information. Example of the Exchange components that use DS
Access are Exchange System Attendant, Message Transfer
Agent and the Exchange information store.
DS Access is a generic name assigned to a group
of DLLs - DSAccess.dll, Dscmgs.dll and Dscperf.dll. These
are collectively called the DS Access or the DS access
cache. The DS Access cache is actually made up of two
seperate caches:
The Configuration Cache - The configuration cache is used
to store information pertaining to the configuration data,
including store and routing objects. It is set to 5 MB by
default.
When the system boots, DS Access initiates a
discovery process designed to identify the AD topology
(primarily related to the site structure), the domain
controllers, and which domain controllers act as global
catalog servers.
DS Access repeats the discovery process every 15
minutes to check for configuration changes and verify that
the known domain controllers are still available. Whenever
Exchange server needs to access a domain controller or a
global catalog server, it consults the DS Access cache to
determine which server is best fit for the job.
The User Object Cache - By default the Exchange Server sets
aside 140 MB for the user object cache, which stores user
object data. Objects within this cache are flushed when the
cache fills up or when the object's TTL expires. The
default TTL for the user object is 5 mins.
This user object cache is designed for preventing
excessive LDAP queries. When the Exchange server needs to
know something about a user, it checks the DS Access cache
first to see if the information is already stored there. If
the information is cached, then Exchange uses the cached
copy instead of issuing an LDAP query. If the required
information is not cached, Exchange has to retrieve the
necessary information from the DC via an LDAP query and it
stores the results in the DS Access cache.
Starting with Exchange Server 2000 Microsoft began using
the AD - Active Directory as the repository for Exchange
related data. So microsoft had to create certain rules to
make sure that the Exchange Server communiated with the AD
in such a way that it did not create excessive network
traffic or overwhelm domain controllers with too many LDAP
requests. ( For beginners i would like to explain this in a
little more detail - whenever Exchange would need any data
from the Active Directory it will use an LDAP query for
geting the data. Now all the data is present in the AD and
AD is present on DCs - that is Domain Controlers, hence
Exchange would be sending LDAP queries to DCs for the data.)
So for controlling the communication between
Exchange and AD; microsoft created a component called the
DS Access. DS Access would act as an intermediary between
the AD and Exchange Server.
Thus, DS is used by all the Exchange components
to query the AD and acquire the configuration and recipient
information. Example of the Exchange components that use DS
Access are Exchange System Attendant, Message Transfer
Agent and the Exchange information store.
DS Access is a generic name assigned to a group
of DLLs - DSAccess.dll, Dscmgs.dll and Dscperf.dll. These
are collectively called the DS Access or the DS access
cache. The DS Access cache is actually made up of two
seperate caches:
The Configuration Cache - The configuration cache is used
to store information pertaining to the configuration data,
including store and routing objects. It is set to 5 MB by
default.
When the system boots, DS Access initiates a
discovery process designed to identify the AD topology
(primarily related to the site structure), the domain
controllers, and which domain controllers act as global
catalog servers.
DS Access repeats the discovery process every 15
minutes to check for configuration changes and verify that
the known domain controllers are still available. Whenever
Exchange server needs to access a domain controller or a
global catalog server, it consults the DS Access cache to
determine which server is best fit for the job.
The User Object Cache - By default the Exchange Server sets
aside 140 MB for the user object cache, which stores user
object data. Objects within this cache are flushed when the
cache fills up or when the object's TTL expires. The
default TTL for the user object is 5 mins.
This user object cache is designed for preventing
excessive LDAP queries. When the Exchange server needs to
know something about a user, it checks the DS Access cache
first to see if the information is already stored there. If
the information is cached, then Exchange uses the cached
copy instead of issuing an LDAP query. If the required
information is not cached, Exchange has to retrieve the
necessary information from the DC via an LDAP query and it
stores the results in the DS Access cache.
Explain the configuration steps required to allow exchange
2003 to send and receive email from the internet consider a
one site multiple server sccnario.
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