I'm new to networking and I'm a little confused so could do with some help.
I am currently using Cisco packet tracer and I am trying to configure a fictitious network. Initially I was just trying to get my network to function as intended, which I managed to do (except for getting both networks to be able to ping the same server) however now I am trying to edit what I have done to enter the details of the specifications I have been given and now I'm stuck.
My problem is as follows;
I have a Web server and DNS server with an IP address of 184.108.40.206 for internet access. The internal LAN network is the Class C IP address: 192.168.255.0 behind the firewall router provisioned with two Ethernet ports for the internal subnetted networks and one for the Web and DNS servers. I also need to think about security so the network also requires one sub-network for Admin and another for the Students.
Initially I configured one of my router port 1 to an address of 192.168.1.1 with a subnet of 255.255.255.0 to serve network 1 (lets call it the admin side).
Next I configured my second router port to an address of 192.168.2.1 with a subnet of 255.255.255.0 (which will serve my DNS server)
Then my third port with an address of 192.168.3.1 with a subnet mask of 255.255.255.0 and the forth with 192.168.4.1 with a subnet mask of 255.255.255.0
Off my first port on the router as mentioned earlier I have my admin network and I have given one of the hosts an IP address of 192.168.1.2 with a subnet of 255.255.255.0 and a default gateway of 192.168.1.1 and DNS server of 192.168.2.2.
Off my second port on the router I have my DNS server. IP address- 192.168.2.2 subnet 255.255.255.0 default gateway -192.168.2.1 and of course the DNS server of itself.
Off the third port on my router I have my Web server with a IP address of 192.168.3.2 and subnet of 255.255.255.0 and default gateway of 192.168.3.1
Lastly I have my fourth port on my router serving the classroom side of the network with a 192.168.4.1 and subnet of 255.255.255.0.
Now when I change my DNS server and Web server to the IP address to 220.127.116.11 it throws out the whole network, I have of course updated the dns server address and applied the new 192.168.255.2 IP on the host computer etc but when I try to ping the server it fails. I'm not sure if its because the gateways IPs I have originally used are not meant to deal with this new IP?
The other question I have is that as mentioned above, I need to split the network, I have researched how to do this and I understand that I need to use a different subnet mask e.g 255.255.255.128 but when I do this, it affects my DNS server since they have a subnet of 255.255.255.0 so how can I get my DNS and web servers to serve both sides of the network? I can stop both sides (admin side and classroom side) from accessing each other fine but I cant figure out how to allow both networks access to the same DNS and Web server.
I have done lots of research to try and avoid asking for help hence how I initially got my network to work but since my question is so long I won't list everywhere. But I have looked for answers here and YouTube etc for clarity but after two days of looking and dealing with all these numbers as a beginner, I'm not having much luck! Any help or guidance would be appreciated.