Default gateway IP for one armed router, DNS, and other questions for SMB setup

[rival9217]

Ok, I posted a similar topic just a couple of days ago and while I got some help, I'm not getting the actual detail I need in full.

What I'm looking to do is hook up a router on a stick for a small business (with internet access so I know NAT will need to be setup as well) and a windows server that will handle the DHCP and DNS.

My questions are:

- For all the following questions - does the ISP provide the IP's (i.e. one for the default gateway and 1 or 2 IP's for DNS)

- What command(s) do I use to set the default gateway IP on the router (keep in mind I'm not talking about setting up "default gateway" or "Gateway of last resort").

- What IP (if not provided by the ISP) would I use for the default gateway entry on the windows server under networking settings?

- What addresses (if not provided by the ISP) would I use for the DNS entries on the windows server?

[Richard Burts · Accepted solution]

The answers to your questions are very much dependent on your particular environment and therefore it is difficult for us to provide the level of detail that you are asking. Here are my answers to your questions:

- usually the ISP will provide an IP address for the interface of your router and an IP address for the default gateway and IP addresses to use for DNS. But what this particular ISP will provide depends on the ISP and depends on what you have negotiated in the contract or Service Agreement that you should have with the ISP. 

- I do not understand your statement that you are " not talking about setting up "default gateway" or "Gateway of last resort"). " If it is not Gateway of Last Resort then what are you looking for? The way that we typically understand gateway IP would be to use ip route 0.0.0.0 0.0.0.0 <gateway_address>. If you are looking for something else then you need to help us understand what it is that you are looking for.

- The IP address that you would use for the default gateway entry on the windows server would typically be the IP address of the router interface of the subnet that connects to the server.

- the IP address that you would use on the windows server for DNS are completely dependent on your particular situation. If you are not using ISP DNS then what do you have set up to provide DNS service? That would be the address to use.

HTH

Rick

[rival9217]

You actually indirectly, answered the question in full.

First, what I meant by "I'm not talking about setting up the default gateway..." was exactly that, I wanted to know if there was another way of setting the default gateway with ISP that I wasn't aware of. I now know that upon receiving the gateway IP from the ISP...I just simply set the gateway IP given by the ISP as the default route for every subnet on every sub-interface I setup.

DNS - yes, I was hoping it was as simple as the IP providing the IP's so thanks for answering that.

And thanks for answering what gateway address goes onto the server....I was assuming it was the ISP's default gateway IP and not the sub-interface IP - so thanks again.

I really appreciate your reply as it honestly did answer everything.

If your curious, here is my original question posted in a separate discussion where I was asking the same questions (someone else helped me out a lot on this as well):

Hey guys and gals - I just wanted to ask (as I literally cannot find the answer to this question anywhere online) what are the names of the cables and ports used to hook up the following (simple) small office network setup that would include a T1 connection, 1 switch, & 1 router:

From the demarc point...what cable and ports are used to hook up the T1 modem to the router, what cable and ports are used to hook up the router to the switch (for both the router and switch).

I'm under the assumption that regular cat 5 goes from the trunk port on the switch to one of the LAN ports on the router but I'm not sure - and I have no idea what cable and ports are used for the T1 modem hookup.

For the DHCP server I would be using in the small office environment: I know how to setup the DHCP helper address on the router so all 3 separate scopes I use for each sub-interface will be routed properly but I have some very basic questions that I technically should know but just honestly don't:

1. after I have everything hooked up....how do I lookup the IP address of the router?

2. when setting up my single DHCP server (with the DNS role installed as well) - do I just select any IP addresses out of the scopes I'm using and set the IP I selected to static (under IPv4 for network settings on the server)? Also, do I select 2 IP's for the DNS entry to set as static as well?

3. Would I need to enter the default gateway address (IP address of the router)on my server config as well?

As always, thanks for any help.

[Richard Burts]

I am glad that I did manage to answer your question in full. Thank you for using the rating system to mark this question as answered. This helps other readers in the forum to identify discussions which have helpful information.

HTH

Rick