In a recent post I showed how to configure the DHCP server with multiple scopes of subnets with PowerShell and how blazing fast that could be done in the Windows 2012 compared to Windows 2008 R2.

One thing we might forget is to populate the Active Directory Sites and Services subnets with this information to get the clients to access the domain controllers that is nearest. As you can read in this technet post the reason for populating this:

“Domain controllers register service (SRV) resource records in Domain Name System (DNS) that identify their site names. Domain controllers also register host (A) resource records in DNS that identify their IP addresses. When a client requests a domain controller, it provides its site name to DNS. DNS uses the site name to locate a domain controller in that site (or in the next closest site to the client). DNS then provides the IP address of the domain controller to the client for the purpose of connecting to the domain controller. For this reason, it is important to ensure that the IP address that you assign to a domain controller maps to a subnet that is associated with the site of the respective server object. Otherwise, when a client requests a domain controller, the IP address that is returned might be the IP address of a domain controller in a distant site. When a client connects to a distant site, the result can be slow performance and unnecessary traffic on expensive WAN links.”

So as we do not want to update 2016 subnets manually we do this with PowerShell instead, and as you can see with the Windows 2012 it goes quite fast (I have tested on Win 2008 R2 and it works there also).

and here is the small PowerShell bits that do the magic

# Populate Subnets in AD Sites and Services
#
# Niklas Akerlund 2013-05-14 

for($b=1;$b -le 63 ; $b++){
    for($i=0;$i -le 255){ 
        $Name = "10.10.$b.$i" + "/29"
        $Description = "10.10.$b.$i" + "/255.255.255.248"
        New-ADObject -Name $Name -Type subnet -Description $Description -OtherAttributes @{location="RemoteVPN";siteObject="CN=HQ,CN=Sites,CN=Configuration,DC=lumademo,DC=local"} -Path "CN=Subnets,CN=Sites,CN=Configuration,DC=lumademo,DC=local"     
        $i = $i +8
    }
}

And then when you look in the Active Directory Sites and Services you will find all the subnets and that they correlate to the right site.

I have had a lot to do and that is why I have not done so much updating on the blog, soon my third article will be published on Petri IT Knowledge 🙂 I have also attended the MMS in Las Vegas where I got loads of good information and meet lots of people!

In this post I want to show you the improvements in Windows 2012 and with the PowerShell native cmdlets in this version.

The task was to automatically create 2016 DHCP Scopes for clients on a DCHP server and every scope was a /29 net with 3 lease addresses and one router for each.

I tested this on a Windows 2008 R2 with the community powershell module  and with the following script it took, and I am not kidding, almost 5 hours!! the module utilise the net sh commands with dhcp and probably there could be a lot of improvements for performance, and seriously, just creating one or two scopes can be done in the gui but doing over 2000 will demand a scripted way!

# Massive DHCP Scope 2016
#
# Niklas Akerlund 2013-04-24

write-host (get-date)
for($b=1;$b -le 63 ; $b++){
    for($i=0;$i -le 255){ 
        New-DHCPScope -Server localhost -Name 10.10.$b.$i -Address 10.10.$b.$i -SubnetMask 255.255.255.248 | Out-Null
        $startip = $i+2
        $endip = $i+4
        $router = $i+1
        Add-DHCPIPRange -Server localhost -Scope 10.10.$b.$i -StartAddress 10.10.$b.$startip -EndAddress 10.10.$b.$endip | Out-Null
        Get-DHCPScope -Server localhost -Scope 10.10.$b.$i | Set-DHCPOption -OptionID  003 -DataType IPADDRESS -Value 10.10.$b.$router | Out-Null
        $i = $i +8
    }
}
write-host (get-date)

With the PowerShell DHCP module for WIndows 2012 I have created the following script for creating the same amount of scopes and configuration and running it took only about 1 minute!!

# Massive DHCP Scope 2016
#
# Niklas Akerlund 2013-04-24

write-host (get-date)
for($b=1;$b -le 63 ; $b++){
    for($i=0;$i -le 255){ 
        $startip = $i+2
        $endip = $i+4
        $router = $i+1
        Add-DhcpServerv4Scope -Name 10.10.$b.$i -StartRange 10.10.$b.$startip -EndRange 10.10.$b.$endip -SubnetMask 255.255.255.248
        Set-DhcpServerv4OptionValue -ScopeId 10.10.$b.$i -Router  10.10.$b.$router
        $i = $i +8
    }
}
write-host (get-date)

As you can see, handling lots of changes and configurations can easily be done in the new Windows 2012 and it´s native cmdlets!