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Asked: 2017-01-19 09:13:14 +0800 CST

How does DFSR work out costs to other sites?

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We have 4 sites - two of which host DFS servers. 

Site A - DFS Server #1 (namespace member, replication group)
Site B - DFS Server #2 (namespace member, replication group)
Site C - No servers, just PCs.
Site D - No servers, just PCs.

By default, clients who access the namespace are referred to the DFS server in their local site. i.e. a PC in Site A will get DFS Server #1 as their referral.

However, a client PC in Site C has no local DFS server.

From a networking perspective, it is cheaper to go to Site A to access the data. But there are no DCs, no servers, therefore no site links, thus no costs. How does DFS work out site costs.

How can I force it to use Site A instead of Site B. Do I need to create AD site links from Site C to Site A with a cheaper cost than Site C to Site B (even though there are no DCs?)

dfs-r dfs active-directory

2 Answers

  1. Best Answer

    The simplest solution would be to add the subnets for sites C and D in ADS&S and associate them with site A.

    Clients in sites C and D will then have affinity with site A and will authenticate with the DC's in site A and will get DFS referrals for the DFS servers in site A.

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  2. I know it's an old question, but I encountered this today as well. Contrary to what was assumed, you actually can set up costs for a site that doesn't have a DC. I do this for some remote sites which are within our enterprise network, but not within my local control. In my case, site C includes our VPN users, and I was using it to steer them to a specific DFS server that has more bandwidth.

    • Keep sites C and D with appropriate subnets as separate sites to match the topology of your network.
    • Create a two new site links that include sites A and C in one, and sites A and D in the other.
    • Set the cost of the new site links lower than your default site link, assuming you have one (the one that includes A, B, C, and D).

    This sets a preferred path for sites C and D. Wait for DFS changes to replicate, or speed things along with the appropriate repadmin /syncall and dfsutil /pktflush commands.

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