Additional domain controller in remote site



  • hi everybody

    i will begin by a brief introduction of my existing topology:

    i have 2 office : main and branch connected together via openVPN (site to site) using 2 pfSense Boxes

    i have a primary DC in the main office, and users in the branch login from this PDC.i

    i have 4 Mbs download and 0.5 Mbs upload

    because of my low bandwidth, i decided to setup an additional DC in the branch office so that the site link will be used only for file sharing and IP cameras ...

    i have 2 different subnet 192.168.1.0/24 and 192.168.5.0/24 for both main and branch

    i go to Active Directory Site and Services and add a new site Branch, and i configure the replication and the site link and the subnet, everything seem correct

    i setup an additional DC (global catalog and DNS server) and set up his ip configuration to use My PDC as his DNS server

    the ADC is added to the branch Site,

    i replaced the DNS ip of my Branch machines (it was before the PDC ip) with the DNS ip of my ADC

    The problem now with the branch machines, they are still loging from the PDC, i flushed the dns but no way, i disconnect the vpn connection then a message telling that no logon server available, which mean that branch machines didn't recognize ADC as a logon server

    please any help will be appreciated



  • The AD box needs access to DNS too. You need to give the secondary DNS server pointing to itself.



  • Is the branch DNS getting its DNS from the primary?



  • @Dashrender said:

    The AD box needs access to DNS too. You need to give the secondary DNS server pointing to itself.

    the main DC need only his own ip as DNS server, but the branch DC need the DNS access of the main DC, do you mean that he need his own ip as a second DNS ??



  • @scottalanmiller said:

    Is the branch DNS getting its DNS from the primary?

    Yes Sir, the branch DC getting its DNS from the main DC,
    i have another problem regarding the replication, normally i set a schedule for the replication so that it will start at night and finish in the morning, but i get shocked to see that the replication take place in real time, it seems that the ADC feel that he is still in the main office,
    i think that i commit a mistake when i promote the ADC in the main office, i think i should promote it while i'm in the branch, so that he will be born in the branch and feel that he is a DC that belong to the branch office,

    i think i should demote it and promote it again in the branch office, any suggestion ???



  • @IT-ADMIN said:

    @Dashrender said:

    The AD box needs access to DNS too. You need to give the secondary DNS server pointing to itself.

    the main DC need only his own ip as DNS server, but the branch DC need the DNS access of the main DC, do you mean that he need his own ip as a second DNS ??

    Any DC should always point to itself for DNS first. Don't confuse the setup of DNS resolution (points to itself) with the setup if the DNS server. Two different things.

    The DNS server has to sync from and to the other DC.



  • @IT-ADMIN said:

    @scottalanmiller said:

    Is the branch DNS getting its DNS from the primary?

    Yes Sir, the branch DC getting its DNS from the main DC,
    i have another problem regarding the replication, normally i set a schedule for the replication so that it will start at night and finish in the morning, but i get shocked to see that the replication take place in real time, it seems that the ADC feel that he is still in the main office,
    i think that i commit a mistake when i promote the ADC in the main office, i think i should promote it while i'm in the branch, so that he will be born in the branch and feel that he is a DC that belong to the branch office,

    i think i should demote it and promote it again in the branch office, any suggestion ???

    I don't believe that that will do anything. It doesn't treat sites like that.

    Is real time replication causing a network strain? It is usually extremely little traffic.



  • A few things:

    1. Each DC should only point to itself for DNS. After turning a member server into a DC, you may need to adjust its DNS settings accordingly.
    2. Each site should have a Global Catalog (GC). Ensure that your new DC is also a GC.
    3. Make sure that the client computers are set to use their local DC as the primary DNS server, with their secondary being offsite.


  • @alexntg said:

    A few things:

    1. Each DC should only point to itself for DNS. After turning a member server into a DC, you may need to adjust its DNS settings accordingly.

    I'll go on the record and say I disagree with this. At minimum every DC should have a secondary IP of another DNS server (assuming you have at least two). Furthermore I typically set my DC's to point to the other DNS server for the primary and itself as the secondary. This allows ADDS to have an active DNS source while booting since local DNS might not be completely up before ADDS starts (if this has been resolved on 2012 I might be a bit behind these days).



  • @IT-ADMIN said:

    @Dashrender said:

    The AD box needs access to DNS too. You need to give the secondary DNS server pointing to itself.

    the main DC need only his own ip as DNS server, but the branch DC need the DNS access of the main DC, do you mean that he need his own ip as a second DNS ??

    Yes. Now Scott and Alex are both saying it should point to itself first, but I prefer to point to another DNS server first, and itself second.

    But - if the DC is only pointing to another source, and you remove that source you will find that the DC in question (in your case the branch DC) will have all kinds of problems since it doesn't have DNS to query about services.



  • @Dashrender said:

    @alexntg said:

    A few things:

    1. Each DC should only point to itself for DNS. After turning a member server into a DC, you may need to adjust its DNS settings accordingly.

    I'll go on the record and say I disagree with this. At minimum every DC should have a secondary IP of another DNS server (assuming you have at least two). Furthermore I typically set my DC's to point to the other DNS server for the primary and itself as the secondary. This allows ADDS to have an active DNS source while booting since local DNS might not be completely up before ADDS starts (if this has been resolved on 2012 I might be a bit behind these days).

    It's a bit of a catch 22. There have been a few times that I've had to put a second DNS server in due to boot hanging. The flip side is that if you have a 2nd DNS server in and its own DNS server fails, how would you know to correct it? You may not notice the issue until the other DNS fails.



  • Assuming the links between locations can handle it, I'd have the another server pointing at this one. As for knowing if there are problems, the local clients will be using the DNS of the local server, in the case of the OP, both servers DNS server will be being used by clients. If there are problems you should find out through complaints from them.



  • @Dashrender said:

    Assuming the links between locations can handle it, I'd have the another server pointing at this one. As for knowing if there are problems, the local clients will be using the DNS of the local server, in the case of the OP, both servers DNS server will be being used by clients. If there are problems you should find out through complaints from them.

    The clients should be set up to use a second DNS server at a different site. If the first one is unavailable, the clients wouldn't notice.



  • @alexntg said:

    @Dashrender said:

    Assuming the links between locations can handle it, I'd have the another server pointing at this one. As for knowing if there are problems, the local clients will be using the DNS of the local server, in the case of the OP, both servers DNS server will be being used by clients. If there are problems you should find out through complaints from them.

    The clients should be set up to use a second DNS server at a different site. If the first one is unavailable, the clients wouldn't notice.

    Assuming that strain isn't to much on the connection..



  • @Dashrender said:

    @IT-ADMIN said:

    @Dashrender said:

    The AD box needs access to DNS too. You need to give the secondary DNS server pointing to itself.

    the main DC need only his own ip as DNS server, but the branch DC need the DNS access of the main DC, do you mean that he need his own ip as a second DNS ??

    Yes. Now Scott and Alex are both saying it should point to itself first, but I prefer to point to another DNS server first, and itself second.

    But - if the DC is only pointing to another source, and you remove that source you will find that the DC in question (in your case the branch DC) will have all kinds of problems since it doesn't have DNS to query about services.

    Microsoft has always stated that it needs to point to itself first. There is no benefit to pointing to the other first but many downsides like higher latency and increased traffic.



  • what about the replication that take place in time, it seems that the branch DC don't respect the Active Directory Sites and Services at all, because i configure the replication to take place at night and finish in the morning

    and how to force branch machines to login from their local DC, ???



  • @IT-ADMIN said:

    what about the replication that take place in time, it seems that the branch DC don't respect the Active Directory Sites and Services at all, because i configure the replication to take place at night and finish in the morning

    and how to force branch machines to login from their local DC, ???

    The default replication schedule of a couple hours should be sufficient for most needs. Any more than that could leave the two sites rather out of sync. Less than that's a waste of bandwidth.

    Is their local DC a GC as well?



  • @alexntg said:

    @IT-ADMIN said:

    what about the replication that take place in time, it seems that the branch DC don't respect the Active Directory Sites and Services at all, because i configure the replication to take place at night and finish in the morning

    and how to force branch machines to login from their local DC, ???

    The default replication schedule of a couple hours should be sufficient for most needs. Any more than that could leave the two sites rather out of sync. Less than that's a waste of bandwidth.

    but at lease the branch DC should respect the schedule, \

    Is their local DC a GC as well?

    Yes it is both a global catalog and DNS server



  • @IT-ADMIN said:

    @alexntg said:

    @IT-ADMIN said:

    what about the replication that take place in time, it seems that the branch DC don't respect the Active Directory Sites and Services at all, because i configure the replication to take place at night and finish in the morning

    and how to force branch machines to login from their local DC, ???

    The default replication schedule of a couple hours should be sufficient for most needs. Any more than that could leave the two sites rather out of sync. Less than that's a waste of bandwidth.

    but at lease the branch DC should respect the schedule, \

    Is their local DC a GC as well?

    Yes it is both a global catalog and DNS server

    Ok, and what is the primary DNS on each client set to?



  • @alexntg said:

    Ok, and what is the primary DNS on each client set to?

    i set client in the main office to use the main DC for DNS resolving and set branch client to use branch DC for DNS resolving



  • what server is providing DHCP for the branch PCs?



  • @IT-ADMIN said:

    @alexntg said:

    Ok, and what is the primary DNS on each client set to?

    i set client in the main office to use the main DC for DNS resolving and set branch client to use branch DC for DNS resolving

    And if you run an nslookup against the branch DC, does it resolve queries?



  • @alexntg said:

    @IT-ADMIN said:

    @alexntg said:

    Ok, and what is the primary DNS on each client set to?

    i set client in the main office to use the main DC for DNS resolving and set branch client to use branch DC for DNS resolving

    And if you run an nslookup against the branch DC, does it resolve queries?

    nslookup in branch client machine or branch DC itself ??



  • @IT-ADMIN said:

    @alexntg said:

    @IT-ADMIN said:

    @alexntg said:

    Ok, and what is the primary DNS on each client set to?

    i set client in the main office to use the main DC for DNS resolving and set branch client to use branch DC for DNS resolving

    And if you run an nslookup against the branch DC, does it resolve queries?

    nslookup in branch client machine or branch DC itself ??

    Nslookup from any client computer, and specify the branch DC as the DNS server.



  • @IT-ADMIN said:

    @alexntg said:

    @IT-ADMIN said:

    @alexntg said:

    Ok, and what is the primary DNS on each client set to?

    i set client in the main office to use the main DC for DNS resolving and set branch client to use branch DC for DNS resolving

    And if you run an nslookup against the branch DC, does it resolve queries?

    nslookup in branch client machine or branch DC itself ??

    Both, actually.



  • @scottalanmiller

    when i run nslookup in any branch computer, it resolve successfully but it use the main DNS even if i they have as primary DNS the ADC ip address
    what anger me is that machines in the branch office neglect the ADC



  • @IT-ADMIN said:

    @scottalanmiller

    when i run nslookup in any branch computer, it resolve successfully but it use the main DNS even if i they have as primary DNS the ADC ip address
    what anger me is that machines in the branch office neglect the ADC

    What happens when you force nslookup to use the branch server?



  • @Dashrender said:

    what server is providing DHCP for the branch PCs?

    Again, what server is providing DHCP to the branch PCs? Is the scope set correctly to give the PC's the DNS of the branch DNS server.



  • @alexntg said:

    @IT-ADMIN said:

    @scottalanmiller

    when i run nslookup in any branch computer, it resolve successfully but it use the main DNS even if i they have as primary DNS the ADC ip address
    what anger me is that machines in the branch office neglect the ADC

    What happens when you force nslookup to use the branch server?

    really i didn't try that, but tomorrow i will go to the branch office and try this, thank you



  • @IT-ADMIN said:

    @alexntg said:

    @IT-ADMIN said:

    @scottalanmiller

    when i run nslookup in any branch computer, it resolve successfully but it use the main DNS even if i they have as primary DNS the ADC ip address
    what anger me is that machines in the branch office neglect the ADC

    What happens when you force nslookup to use the branch server?

    really i didn't try that, but tomorrow i will go to the branch office and try this, thank you

    You can try it from your computer, even. Just force nslookup to use the branch DC.