Page 114 - Lakeland Catholic Technology Plan

13.3 DNS Services
Another major user of bandwidth is DNS requests. As is quite well known, the Internet is merely a network of IP addresses. However, very few people are interested in remembering the numeric address, so instead they remember a domain name address. This domain name address, like for example: www.ualberta.ca is much simpler to deal with. But, each time a user wants to go to that website, the computer has to convert from www.ualberta.ca to it’s numeric IP address. These conversions are called DNS lookups.
In the District, when a computer does a DNS lookup, each request goes out to the Internet for a conversion, and this numeric IP address is returned to the requesting computer. Again, like web site lookup, this is a repetitive and duplicating task. The District does not have it’s own DNS server, so every time they need to look up an address, the request goes out to DSI, thus taking up bandwidth. A DNS server is a computer that sits on the network and all it does is store tables of names to IP ad- dress conversions. Like a proxy server, it holds the data so if another user wants to look up the same site, they don’t have to make the same DNS request to the outside Internet world. Now when computer A looks up www.yahoo.com, the ac- tual address is stored in the DNS server, so when computers B through Z look up www.yahoo.com, they get the address from the local DNS server, instead of hav- ing to travel to the Internet to find it. DNS servers are relatively cheap, and easy to implement. In fact it comes with Windows NT Server, and there is a Windows NT server in each school, so it would be very simple to implement.
The District has gotten away with not having a DNS server by creating a local HOSTS file. This file is placed on every single computer, and it has a conversion lookup for the local proxy server, thus avoiding the need to do a DNS lookup. This solution however is problematic at best. If at any time there is a need to change the network address of a computer, the HOSTS file has to be modified in every single workstation. This is a very tech support intensive task. Whereas if a DNS server was installed, the change would have to be made only once on the main DNS server, and it would replicate automatically everywhere else.
Recommendations:
1. The District should install DNS server software in each of it’s Windows NT Servers throughout the system. The school DNS servers should look to the District DNS Server for all lookups.
2. The District should eliminate the HOSTS files from the workstations, and from their routing of technical maintenance.
13.4 DHCP vs. Manual IP Addressing
In order for a computer to access the Internet, it needs to have a unique number assigned to it. This number is called an IP address. There are a number of different ways of assigning this number. Two of the most common methods are manual and by DHCP. Manually assigning an address requires someone to sit down at every computer and assign it a unique address. This is time consuming, and requires lots of organization, as you need to remember which machine has which address. And, any time a computer is reloaded, or has some software like the Operating System reinstalled, the address has to be manually entered again, and it must of course not be a duplicate. This requires significant paperwork, and way too much technical support.
The preferred method for assigning IP addresses is via a DHCP Server. (Dynamic Host Control Protocol) In this method, a computer is setup with a list of available addresses. Then, whenever a workstation wishes to use the Internet, it requests
an IP address from the DHCP Server. When it is finished using the address, it re- turns it to the DHCP Server. Then the DHCP Server acts as the network administra- tor assigning addresses as needed, and keeping track of which addresses are available.
The District has implemented a DHCP server in each school, which is an excellent design plan, allowing staff to save significant time in setting up computers to ac- cess the Internet.
Recommendation:
1. Maintain status quo with respect to DHCP services.
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