have a few basic networking questions, servers and LANs

Sure... the problem you face is bandwidth - opening large files - even not so large files can take several minutes, depending on the application and file.  All you need is a hardware VPN to connect the two sites and the workstations can all work off of one server.  IDEALLY, you will set up Terminal Server... but from security and best practices standpoints, you would then want at least TWO servers (they would both be at the same site).  Further, using this model, you could end up having problems where one site is COMPLETELY unable to work if the connection fails.

You could setup a system like I just did where a client of mine has one server at each site and uses DFS to replicate data.  This replication ensures that both sites have identical data so if one site fails, the other site can keep working - or if the link fails, both sites can keep working, at least in part.  

Keep in mind, being cheap today (with one server) could cost you MUCH more later - an outage could result in a site being down a day when if it had its own server, it wouldn't have to be - and if a site goes down, how much money are you losing because your workers cannot work and take orders.... Save $2000 on a server today... lose $10,000 of sales 6 months later when the link goes down and everyone is forced to sit on their hands and wait for the link to come back up.

leew,
thank you very much for replying.

so if I have this central server in 1 state for example and load client/server app on it whose service runs on this central server only, will the client machines in a different state be able to launch their client application inteface and be able to read the service on this central server.
can you tell me a bit of how that works, (how all these LAN's in different states interconnect and establish a connection) I do not need very technical details as I am not setting this network up I need to know how this all works in very laid back terms :)

thank you very much

Basically you have two options -
VPN or private network
The private network is a bunch of T1s or better that physically connect all the offices together, then with the right hardware you could have all the offices be the same LAN - all the addresses could be in the same ip space - like 192.168.1.0 255.255.0.0
Alternately you could go with a VPN - then each site has internet access and a vpn router which when programmed will create secure private links between the offices. In this instance all the offices must have different ip spaces and the routers are programmed to send private traffic through the vpn tunnels through the internet to the appropriate office.
The cost is lower, typically, for the VPN solution, and you may be able to have multiple internet connections at the central server so that if one went down you could still have all the offices working.
The VPN gear you use will depend on your connection types and bandwidth.
Does that help?

My recommendation would be to get some hardware VPN devices, such as Netgear FVS114 devices (which I just installed).  These devices would then be configured to establish an always-on VPN connection that would essentially link one office to another.  It was quite easy to setup and it's been working quite well.

Just a followup note on a point made by DarthBGP - the FVS114 devices are limited to slightly over 2Mbit links between sites (your actual speed from your ISP can be higher, just these devices will max out at 2.1 Mb.  More expensive devices, I believe a Netgear FVS 338, for example, will handle MUCH faster connections but, of course, costs more.  If you're using T1's or DSL at both ends, then the 114 is almost certainly just fine.

leew,
It's good to see for once someone using Netgear equipment and not going on about expensive and unnecessary Cisco equipment!
-tigermatt

Actually, I'd prefer a UTM device such as a fortigate box, but my client doesn't have the budget for that right now ($1500-$2000 for the two that would be needed; Netgear's were $50 TOTAL).

DarthBGP,
can you tell me what would be the terminology for asking "in instances where there is 1 central server spanning multiple states in 1 country" do you have a central server spanning multiple connected LAN's?
I need to ask a question about how are all these lan's in different states connect to 1 central server?

how to answer a question of how much bandwidth is needed for the application to run (app runs 200+ mbs's on the server) --
do you have a dial up or a dedicated connection?

thank you

Systems Ax,
I'm not sure I understand your question.
I wouldn't use dialup connections for any Microsoft application, nor most database apps.
If the app needs to transfer 200+MB you'll need really big pipes - in the range of 100 Mbps each - most times that's not the case. That 200 MB app on the server may only need 100Kbps per remote user to access and use.
 

does VPN use a dial up connection or can it use a dedicated line also?
thank you

Wow, so my comments didn't help you at all?