Subscriber Modem DNS setting

Hi all,

If you setup a Subscriber Modem to use NAT, have DHCP server enabled and DHCP client disabled, should you be able to set the DNS setting to obtain automatically? I tried this but it wouldn’t work - I couldn’t browse from the computer but if I set it manually then it does work.


I remember discovering the same thing when I was first playing with those features. It seemed like a lack of basic functionality. Since I did not indend on using NAT or DHCPD in the SMs, I did not really care and just moved on.

When you ask about DNS being set to automatically, are yuo asking for the computer connecting, or the radio? The radio as far as I have seen can pick up the DNS automatically, with and without the DHCP client set, but if you have anyone else on your network accidentally spewing DHCP besides the ISP all bets are off. If you set them manually in the radio, sometimes the computer will not pick it up. Also the DHCP server on the radio is a bit slower than coming from a separate router I have found. But it does work.

What I was asking was that regardless of whether the DNS was being set automatically or manually on the radio, if the radio is acting as a DHCP server for the computer would you expect the computer to receive the DNS address from the radio? As far as I could tell, when the radio was setup to receive the DNS automatically, the DNS address was not being passed onto the computer.

Currently our SM’s pull from a dhcp server, then the sm itself issues nated dhcp address’s like a router. When set to auto detect dns, the computer behind the sm is seeing our dns servers.

So I would imagine it depends how things are setup.

DNS addresses can be passed to a host – either PC or SM – but it only works if the primary IP address is also being obtained automatically. DHCP does both.

Test it in Windows XP: When the option “Obtain Address Automatically” is selected, then both DNS options are available. When “Use The Following IP Address” is selected, then only the “Use The Following DNS Server Addresses” option is available.

The Canopy SM works the same way, but its interface doesn’t make this clear.

Thanks Teknix,

I think that was what I was suspecting but wasn’t quite sure about,