“The LastLogonTimeStamp Attribute” – “What it was designed for and how it works”
Warren here. In Windows Server 2003 we introduced the lastLogontimeStamp attribute. Administrators can use the lastLogontimeStamp attribute to determine if a user or computer account has recently logged onto the domain. Using this information administrators can then review the accounts identified and determine if they are still needed and take appropriate action.
It is important to note that the intended purpose of the lastLogontimeStamp attribute to help identify inactive computer and user accounts. The lastLogon attribute is not designed to provide real time logon information. With default settings in place the lastLogontimeStamp will be 9-14 days behind the current date.
If you are looking for more “real-time” logon tracking you will need to query the Security Event log on your DC’s for the desired logon events i.e. 528 –Windows XP2003 and earlier or 4624 Windows Vista2008 . See this blog post by Eric Fitzgerald for more info. (I think he knows something about auditing)
IMO your best bet for near real-time data is to use an event log collection service to gather all domain controller security event logs to a centralized database. You can then query a single database for the desired logon events. Microsoft’s solution for security event log collection is Audit Collection Services. There are many 3rd party solutions as well.
How it worked in Windows 2000
Prior to Windows Server 2003 administrators had to query the lastLogon attribute to determine the most recent logon of user or computer account. This process was time consuming as the lastLogon attribute is updated only on the DC that validates the logon request. The lastLogon attribute is not replicated. So in the past to determine the most recent logon of a user or computer account the lastLogon attribute had to be queried on all domain controllers (at least in concept) and then the most recent date for lastLogon had to be determined from all the results returned. In Windows 2003 and higher lastLogon is still has the same behavior. It is updated only on the validating DC and is not replicated.
How it works in Windows Server 2003 and later
In contrast the lastLogontimeStamp attribute is replicated so all DC's have the same value for the attribute (after replication convergence). Therefore you can query a single DC to find all the users or all the computers that have not logged in within a certain time.
Your Windows domain must be at Windows 2003 Domain Functional Level for updates to the llastLogontimeStamp to occur.
Logon types and that will trigger an update to the lastLogontimeStamp attribute.
The lastLogontimeStamp attribute is not updated with all logon types or at every logon. The good news is that the logon types that admins usually care about will update the attribute and often enough to accomplish its task of identifying inactive accounts.
Interactive, Network, and Service logons will update the lastLogontimeStamp. So if a user logs on interactively, browses a network share, access the email server, runs an LDAP query etc… the lastLogontimeStamp attribute will updated if the right condition is met. (The conditions are discussed below in the section Update and Replication of lastLogontimeStamp.
As of Windows 2003 SP1 these logon types will NOT update lastLogontimeStamp
- Certificate mapping through Microsoft Internet Information Services (IIS).
- Microsoft .NET Passport mapping through IIS.
[Update June 19, 2009 - removed one item from the list above that is under debate in a repro currently. Will update when we have more word]
Update and Replication of lastLogontimeStamp
First become acquainted with the ms-DS-Logon-Time-Sync-Interval attribute. It is an attribute of the domain NC and controls the granularity (in days) with which the lastLogontimeStamp attribute is updated. The default value is 14 and is set in code. Meaning that if you look at this attribute in ADSIEDIT.MSC and you see it as "Not Set" don't be alarmed. This just means the system is using the default value of 14.
The lastLogontimeStamp attribute is not updated every time a user or computer logs on to the domain. The decision to update the value is based on the current date minus the value of the (ms-DS-Logon-Time-Sync-Interval attribute minus a random percentage of 5). If the result is equal to or greater than lastLogontimeStamp the attribute is updated. There are no special considerations for replication of lastLogontimeStamp. If the attribute is updated it is replicated like any other attribute update. This is not urgent replication
Walkthrough of a lastLogontimeStampUpdate update
1. (Assuming the value of the ms-DS-Logon-Time-Sync-Interval is at the default of 14)
2. User logs on to the domain
3. The lastLogontimeStamp attribute value of the user is retrieved
4. 14 - (Random percentage of 5) = X
5. Current date - value of lastLogontimeStamp = Y
6. X ≤ Y - update lastLognTimeStamp
7. X > Y - do not update lastLogontimeStamp
Why the Randomization?
This randomization is done to prevent an update of the lastLogontimeStamp attribute from many accounts at the same time causing a high replication load on the DC's. Remember the purpose of the lastLogontimeStamp attribute is locate inactive accounts not provide real-time logon information.
Controlling the update frequency of lastLogontimeStamp.
It is possible to change the frequency of updates to the lastLogonTime stamp or turn it off completely if desired. If you need a different time interval you will need to adjust the value of the msDS-LogonTimeSyncInterval attribute to a value between 5-100,000. Yes that’s right: the max value is 100,000 days… Or if you prefer ~280 years... And the max value was set in code not in the schema. (I guess the dev was counting on medical science to solve that pesky aging problem.)
In my experience the default settings can accommodate almost anyone and there is no need to change the update interval. Most customers I have talked to start considering accounts potentially inactive at the 30 day or higher mark of inactivity.
Note: If the msDS-LogonTimeSyncInterval is less than 5 days, the randomization is not put into effect.
How do I turn this thing off?
If you want to disable the lastLogontimeStamp feature set the msDS-LogonTimeSyncInterval attribute to 0.
I personally have never spoken with anyone that really had a business need to change how often lastLogontimeStamp needs to be updated. Once it was explained how the update process works and it was proven that the attribute is current and replicated to all DC’s that was all that was needed. If really think you need a more recent timestamp than 9-14 days for inactive account detection I suggest you make small changes and monitor DC workloads. This is especially true in large environments.
Clearing up the confusion - Verifying that LastLogontimeStamp is in sync across all DCs in the domain.
Many times customers will be concerned about what their tools are displaying to them (usually a very old date) as the lastLogontimeStamp of a user compared to what they know to be a more accurate date. This is almost always due to the admin using a tool that queries the lastLogon attribute instead of the lastLogontimeStamp attribute.
For example acctinfo.dll that is included with the Account Lockout tools will display the lastLogon attribute data not the lastLogontimeStamp data. In some cases the date the tool reports may be months or years out of date or display nothing at all. This is because they are querying the lastLogon attribute and the user they are looking up has either never been authenticated by the reference DC (in the case of null) or has not been authenticated by the reference DC in a very long time.
How to tell if lastLogontimeStamp is in sync
To verify if the lastLogonTime stamp is being updated and replicated as expected you can use repadmin.exe with the showattr switch. Some examples are given below. These examples are intended to demonstrate that lastLogontimeStamp is being updated within the window of 9-14 days and replicated to all DC’s in the domain. They are not an example of how to manage stale accounts.
1. Using repadmin to check the value of lastLogontimeStamp on all DC's in a domain for one user:
repadmin /showattr * (DN of the target user) /attrs:lastLogontimeStamp >lastLogontimeStamp.txt
repadmin /showattr * CN=user1,OU=accounting,DC=domain,dc=com /attrs:lastLogontimeStamp >lastLogontimeStamp.txt
2. Using repadmin to dump the lastLogontimeStamp for all users in a domain including users that have no data in the lastLogontimeStamp attribute:
repadmin /showattr * /subtree /filter:"(&(objectCategory=Person)(objectClass=user))" /attrs:lastLogontimeStamp >lastLogontimeStamp.txt
3. Dump lastLogonTime stamp for users but only ones that have the attribute populated
repadmin /showattr * dc=domain,dc=com /subtree /filter:"((&(lastLogontimeStamp=*)(objectCategory=Person)(objectClass=user)))" /attrs:lastLogontimeStamp > lastLogontimeStamp-2-22-2009.txt
- Warren ‘For Once not DFSR’ Williams