Course13:IT Advanced 2 - 09 Using a custom DNS on your mobile phone

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For the Reverse Proxy lesson, you will need to use a custom DNS on your mobile phone. Here is how.

Why use a custom DNS?

During the Reverse Proxy topic, we want to simulate a branch connected to the real internet. This includes
  • the internet
    which will be simulated by your own local area network
  • the branch router
    which is connected to the (simulated) internet by the IP411RIGHT
  • the worldwide DNS system
    which is simulated by the DNS service on your IP411RIGHT (so your mobile phone can find hq.dvl-ckl2.net)
  • a customer's branch network
    which is simulated by your trainee network

For this to work, the names of your services (e.g. hq.dvl-ckl2.net or apps.dvl-ckl2.net) must be resolved to the IP address of your PBX and App Platform. For the devices within your trainee network (e.g. your PC), this is already the case cause they use the DNS server on your IP411RIGHT.

However, to simulate remote access to your system, we need a device that is not located within your trainee network. So we use your mobile phone connected to your corporate network via WLAN. However, your mobile phone would normally not use the IP411RIGHT's DNS server but a standard DNS server (either your own company's DNS or the DNS of your provider or any publicly available DNS such as google's 8.8.8.8).

Therefore, we need to modify the settings on your mobile phone to also use a different DNS - your IP411RIGHT.

How to determine your DNS server address

The server address is the IP address of the ETH0 interface of your IP411. You can see that on

But what if I have no mobile phone or no WLAN in my corporate network?

Don't worry, if you can't access your corporate network from your mobile phone via WLAN, you may also connect your laptop to your coprorate LAN (using WLAN or Ethernet).


However, keep mind that
  • you need an extra switch port on the same LAN your IP411RIGHT is connected to (more precisely, where the ETH0 is connected to and what we refer to as corporate LAN)
  • you may need to change your laptop's LAN connection from your trainee network to your corporate network and vice versa once in a while
  • you should not connect your laptop to both your corporate network and your trainee network at the same time

Custom DNS on iOS

iOS on your Apple iPhone (or iPad) allows you to override the DNS settings received by DHCP.

Here is how:
  • open the open the global Settings
  • open the screenshot.png Wi-Fi settings
  • click on the screenshot.png little i next to the currently active WLAN interface
  • open the screenshot.png DNS / Configure DNS settings
  • change the screenshot.png DNS mode to manual
  • add the external IP address of your IP411RIGHT as new DNS server and remove the old one
  • save all settings

Custom DNS on Android

Unfortunately, Android does not let you change your DNS settings easily. Most often, a so-called DNS changer App is used. The drawback however is, that these Apps come and go and also sometimes change their pricing policy.

We therefore rather recommend to use a little dirty trick: change your IP mode on the WiFi interface from DHCP to static.

(Further Hints) WARNING: as said before, this is a dirty trick! It is absolutely essential that you revert the settings each evening! Otherwise you may create issues with duplicate IP addresses in your network.

Obtain your current IP settings

First you need to see how your mobile phone's WiFi interface is configured right now.

Here is how:

Set special options for for your training

To modify your network settings:
  • go back to Network Info
  • press long on screenshot.png the Wi-Fi network you are connected to
    a context menu will be shown
  • select screenshot.png Modify network
  • scroll down and open screenshot.png Advanced options
  • change
    • IP settings from DHCP to Static
    • IP address to the value you took note of before
    • Gateway to the value you took note of before
    • Network prefix length to the length that corresponds to the Subnet mask value you took note of before:

      Subnet mask
             		Network prefix length
      255.255.255.
      		 24
      255.255.0.0
      		 16
      255.240.0.0
      		 12
      255.0.0.0
      		 8
      other value
      		 consult your network administrator

    • DNS 1 to the external IP address of your IP411RIGHT

Reset your settings to defaults

It is absolutely essential that you revert the modified settings to the original values each evening!

To do so

Verifying your DNS setting

To verify your new DNS setting, open the browser on your mobile phone, enter http://test.my.dns into its address line and open the site.

You should now see the moodle home page and the address line should read http://test.my.dns/moodle2/?.
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