Thanks, that’s helpful. You read that correctly, except that 192.168.17.0/24 was not defined separately since it is covered by a catch-all subnet. I meant that this was the subnet I tested from within the main site.
*From:* [email protected] [mailto: [email protected]] *On Behalf Of *Damien Solodow *Sent:* Tuesday, February 7, 2017 5:45 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site A few references that may help: https://blogs.technet.microsoft.com/askds/2011/04/29/sites-sites-everywhere/ https://technet.microsoft.com/en-us/library/2009.06.subnets.aspx This is how I’m reading you have it setup; please correct me if I’m wrong. J AD Site 1 (main office), with following subnets defined and associated: 10.0.0.0/8 (catch-all) 172.16.0.0/16 (catch-all) 192.168.0.0/16 (catch-all) 192.168.17.0/24 (actual subnet) AD Site 2 (AWS) with the following subnet defined and associated: 10.0.0.0/16 (actual AWS subnet) If that’s correct, (and AD Sites & Services at both sites shows it as such), you should have the desired behavior. However, if there is an old/incorrect site locater DNS record (see first link), you may get unexpected results till it gets cleaned up. DAMIEN SOLODOW IT Engineering Lead 317.447.6033 (office) HARRISON COLLEGE *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Michael B. Smith *Sent:* Tuesday, February 7, 2017 4:44 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site I’m sorry, I don’t have time to look it all up and cite chapter and verse. Perhaps Brian can chime in and he has it all handy. If you try it as I suggest, I bet it’ll work. My team’s out. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Charles F Sullivan *Sent:* Tuesday, February 7, 2017 4:01 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site Thanks. I just spotted a typo I made where I should have typed “ 192.168.17.0/24”. Unless you are referring to that, I don’t see how I’m not using the catch-alls as intended. *From:* [email protected] [mailto: [email protected]] *On Behalf Of *Michael B. Smith *Sent:* Tuesday, February 7, 2017 3:00 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site Catch-all subnets (also known as supernets) are absolutely supported, but you are not using them the way they were intended. TL;DR; have a separate subnet for the AWS site and everything will be peachy (except when/if all AWS DCs are down). Brian’s book has great coverage on these topics, but it’s really 3 different topics. You need to understand “catch-all subnets”, “automatic site coverage”, and the “DC locator process” – especially what happens to a computer that was moved between AD sites. Those are 3 search terms that will give you great information. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Charles F Sullivan *Sent:* Tuesday, February 7, 2017 2:34 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site I’ve only been able to do very limited testing. - I had about 8 member servers in a site which were actually all in the same subnet as each of and the one DC we had for testing, let’s call the subnet 198.168.17.0/24. In that site I included the usual private ranges: 192.168.0.0/16, 172.16.0.0/12 and 10.0.0.0/8 - At AWS I had a subnet with one DC and just a couple of member servers in the 10.0.0.0/16 subnet, which was defined as the only AWS site. Note that the AWS subnet is a subset of one that I defined at the main site, but this absolutely is supported by MS and others have told me that this works for them. Despite all of this I did see one member server in the main site use the AWS DC after a reboot even though the local DC was clearly present and being used by the other member servers. So that means 1 out 8 member servers I had for testing crossed sites. This made me wonder how often it might happen in our production environment where there are thousands of member computers. I do have to say that I recently got to test this again, this time having 5 DCs at the main site and 2 at AWS. Again, I had just a handful of member servers and a workstation and this time I didn’t see any of them using an AWS DC. The AWS admin didn’t see his one member server use anything besides an AWS DC. *From:* [email protected] [mailto: [email protected]] *On Behalf Of *Michael B. Smith *Sent:* Tuesday, February 7, 2017 1:32 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Blocking AD Client Traffic to a Certain Site Doesn’t make sense to me. The only reason you should have cross-site connections at this point is because you don’t have all of the relevant subnets defined in ADS&S. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Charles F Sullivan *Sent:* Tuesday, February 7, 2017 11:40 AM *To:* [email protected] *Subject:* [NTSysADM] Blocking AD Client Traffic to a Certain Site I’d like to get some ideas and opinions regarding this, especially if anyone has had a similar need….. Our AD topology to this point has been as simple as can be. Since just about everything on our extended network is connected at high speeds, we have never had to have more than one AD site. We are about to put a couple of DCs at AWS, which of course will require a second site to be defined. This will still be pretty straightforward. Everything but AWS will be on the one existing site and a second site will be added for the one subnet at AWS. I know that even with the two sites defined, some clients may at times use the remote site. This is what I have seen in testing, for whatever reason, but I don’t consider it to be a real problem because I assume it would not happen often. The problem is that our director wants absolutely no cross-site traffic except in the case of a disaster. It is being proposed that the firewall between the sites allow only AD traffic between the DCs themselves. AD clients would be stopped at the firewall. I’m not comfortable with that as a solution because I’m concerned that when clients do try to use DCs at the remote site, it will cause slowness if not failure. Does this seem like a bad idea for that or any other reason? I was thinking that maybe I could use weight and priority within SRV records so that the DCs at AWS would be weight=0 and priority=65535. If I did that, would the clients at AWS honor the site rules over the SRV records weight and priority? I’m guess that would be unpredictable, thus also not a good solution. Thanks in advance for any help. Charlie Sullivan Sr. Windows Systems Administrator
