[cifs-protocol] [REG:210050354365053003] more ms-dfsc.pdf questions

[Obaid Farooqi]

Hi Matthieu:
We have finished our investigation on your question regarding the registry parameter effecting DFS referral and the storage of in-site settings. I have arranged the information in question answer format for clarity as follows. I have also attached a PDF file to highlight the additions.

Q. Well here my question was more about the parameters, for instance the least-expensive parameter is called SiteCostedReferrals and is stored in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dfs\Parameters\.
At least there is the same-site parameter that influence the way DFS referral are answered, where this parameter is stored ? Is there any other parameter that influence DFS ?

A. The parameter for in-site (same-site) targets is stored in Active Directory in as follows:
	For DomainV1-Based DFS Namespace, the in-site setting is stored in PKT_ENTRY_TYPE_INSITE_ONLY bit in DFSRootOrLinkIDBLOB metadata, as specified in section 2.3.3.1.1.2 of MS-DFSNM

	For Domainv2-Based DFS Namespace, the in-site setting is stored in InsiteReferral attribute as specified in section 2.3.4.2 of MS-DFSNM.

A future release of MS-DFSC will include the following additions:

3.2.5.5   Receiving a Root Referral Request or Link Referral Request
---------------------------------------------------------------------------------

If DFS in-site referral mode is enabled on the root, root referrals and link referrals return only targets that are in the same site as the client. If no root or link targets exist in the same site of the client, then no referral is returned and the client cannot access that portion of the namespace. If this setting is enabled on a link, and no link targets exist in the same site of the client, then no referral is returned and the client cannot access the link.
	
3.3.5.3   Receiving a DC Referral Request
-----------------------------------------------------
If preferred logon is enabled on domain controller <WBN 1>, then the server MUST place itself on top of the DC referral response  

<WBN 1> On Windows-based domain controller preferred logon is enabled by setting PreferlogonDC value in the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dfs\Parameters\ to 1 (see MSKB-831201).


3.3.5.4   Receiving a sysvol Referral Request
-----------------------------------------------------
If preferred logon is enabled on domain controller<WBN 2>, then the server MUST place itself on top of the DC referral response  

<WBN 2 > On Windows-based domain controller preferred logon is enabled by setting PreferlogonDC value in the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dfs\Parameters\ to 1(see MSKB-831201).



After the addition of the parameter mentioned above, all the registry parameters that effect DFS referral are documented in MS-DFSC.



Q. 
	> Q. Ok so we consider that a client not within a site has all the DCs out of his site right ?
	>
	> A. If the client has no IP address to Site mapping in AD, then the targets in the referral response would be sorted randomly.
	>    
	Ok, that's clear. Does the "same site" setting have an influence on this ?
	Will this information be added somehow in the MS-DFSC ?

A. As I have already communicated in an earlier email, same-site (in-site) setting has no effect on DC referral. The additions to MS-DFSC mentioned above make it clear that in-site setting only effect root and link referrals.

My answer "If the client has no IP address to Site mapping in AD, then the targets in the referral response would be sorted randomly." is drawn from the following additions to MS-DFSC that I have already communicated in an email dated May 11, 2010:

3.3.1.1 Algorithm for sorting target sites in referral response based on site location
     DFS server places target servers in the referral response in the following order:
	-  Targets in the same site as the client are listed at the top of the referral response in random order.
	-  Targets outside of the client's site are appended to the response in random order.

Please let me know if it answers your questions. If it does, I'll consider this issue resolved.

Regards,
Obaid Farooqi
Sr. Support Escalation Engineer | Microsoft


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