Internal IP settings in Server Setup

This is a newbie question but I would like it answered. If you are setting up a server for the first time and you have connected your server to the internet and you plan on having your server be both the dhcp and the dns server for the network, does it matter what IP scheme you use? That is, is there any relationship between the connection between the server and the internet and the IP addresses you set up for the network? If I have setup a connection to the internet with my server and I set a as the static IP for the server, then set dhcp to hand out addresses between to to connected computers, there is no relationship between that internal setup and the external connection to the internet correct?
John MahoneyAsked:
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MdlinnettConnect With a Mentor Commented:
It depends on the subnet mask you use.

A subnet mask of will allow any IP address between and to communicate on the network, regardless of the DHCP scope.

With the scope of 5 - 100 it means you have plenty of spare IP addresses that you can assign to IP phones, printers, CCTV, Servers, wireless access points etc without taking up IP addresses from your DHCP scope.

DHCP reservations can be created for IP addresses that fall outside of your DHCP scope.
John MahoneyAuthor Commented:
Is the subnet mask determined by any outward facing settings on the server or can you just select the subnet mask depending on the network scheme you want? I guess my question is, I somehow got it in my head that the outward settings used by the server to access to the internet played some role in determining what your inward IP network. But as long as you select the correct subnet mask you can choose your own network scheme correct? Thanks
How many network cards are you using on the Server?

Is your Server acting as a Router or do you have a separate Router?

Typically, the default gateway IP will be the IP address of your Router / Firewall.

The Server will provide Client PC's with IP addresses (including the default gateway and DNS Server IP address(es)) via DHCP.

DNS on the Server will route Client PC requests internally, any DNS requests it can't resolve (ie; will be forwarded to the default gateway.

If you have a separate Router / Firewall or NAT device, any external IP address settings are configured there.  The Server technically doesn't know about the external IP address, but the NAT device just forwards anything external to (for example) the public External IP of to your Server's Internal IP of

The subnet mask can be based around your network size... how many IP addresses you require and will require in the future.  They can also be used to segregate parts of the network.

Your internal network is your internal network, use whatever IP address range you like.
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John MahoneyAuthor Commented:
Thank you for clarifying. This is a server 2012 Essentials, I set it up originally so that DHCP was handled by the router, it was a very small network with 3 Home versions of Windows 7 and 2 Pro versions. I set the IP address of the server to be static using the one handed out by the router 192.168.x.x.
Everything seemed to work fine. But now they are growing and going to be adding 10 more computers and a new printer. I'm going to need to upgrade from Essentials to Server 2012 and we're getting rid of the home systems so we can fully join to the domain. Structure is pretty simple with one router, one netgear switch (we'll probably add another one though) and I've heard that even though essentials allows the router to handle DHCP when I move to Server 2012 it's best to use DHCP on the server as well as DNS. My plan was to install DHCP with reservations for printers and other devices, and then point to the server (instead of the router) for client computers to get their addresses. I planned on using for server and use for subnet as we're not going to need anywhere that many addresses. So, as I said for some reason I had it in my head that if you used the server for DHCP you had to set your Internal addresses based on some variable. Don't know where I got this but just being sure! Again thanks for your help.
John MahoneyAuthor Commented:
Thank you for your help greatly appreciated
Happy to help. :)

Essentials is good for 25 domain joined computers FYI.

If you like the essentials dashboard you can install the windows server essentials experience (WSEE) Role from Server manager. This will give you the same look and feel but within standard 2012 r2.
David Johnson, CD, MVPOwnerCommented:
Typically, the default gateway IP will be the IP address of your Router / Firewall.
Any address that is not in your network range will go to the gateway.

DNS on the Server will route Client PC requests internally, any DNS requests it can't resolve (ie; will be forwarded to the default gateway. not strictly true. DNS requests will still be handled by the DNS server for every address.  Internally on the DNS server it will use forwarders or root hints servers for addresses not in its table of address to  get the ip address and then the DNS server will return the address to the requesting client.
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