DNS is the method that the Internet uses to convert Uniform Resource Locators (URLs) to ip addresses; for more information see http://en.wikipedia.org/wiki/Domain_name_system

In schools there are two reasons for DNS:

• resolving internal computer names (such as servers and active domain names) to their IP address

• resolving external URLs (web addresses) to their IP addresses.

The latter is usually handled by the proxy server that your system uses

The former is handled by your main file server, usually the curriculum file server.

There may be occasions where DNS is required by a piece of software which is not covered by the two descriptions mentioned above, such as when using FTP or video conferencing software. To allow these to work there should be a coherent managed DNS in place in your school.

The approach recommended by Broadband Sandwell (because it works) is as follows:

• A workstation will be told initially where to obtain DNS from the school's DHCP server. Query this to check that your initial DNS server is listed here, using the command prompt (start..run..cmd), type ipconfig /all in the dialogue window.

  • There should be one DNS server listed here, this is usually the school's curriculum server. If there are other entries, remove all extra servers from the DHCP console of the DHCP server.

• On the DNS server listed in the DHCP, load the DNS Server console, and find the server icon in the left hand pane.

  • Right click this icon, and choose Properties from the menu. A properties dialogue window will open.

  • In this window, click the Forwarders tab. Here you can enter the IP address of the forwarder, which is the next DNS server on your network. This allows a chain to be formed where DNS requests are passed between servers until the resource name can be resolved.

  • We recommend the following hierarchy of DNS servers:

  • • first, the main curriculum server, usually 172.18.nnn.1, forwards to:
    • the SIMS server, forwards to:
    • the Internal Proxy server, 172.18.nnn.9, forwards to:
    • the Broadband Proxy server, 172.28.21.246
  • If your schools does not have one or other of these servers, ignore/bypass these in the forwarder setting on the previous server.

 

• Once your DNS chain is complete, flush any previous DNS settings (in the command prompt, type ipconfig /flushdns), then check by carrying out a DNS resolution on the workstation, such as by PINGing a URL:

ping www.bbc.co.uk. (Note: the ping will not return any results, but will turn the domain name into its corresponding IP address.)

• The software which previously failed should now function. (or at least, the cause of failure is not your DNS).