DHCP *AND* DNS with Ethernet Shield Library

Projects Networking, Protocols, and Devices
1

DHCP AND DNS with Ethernet Shield Library

Referring to the Repeating Web Client sketch example provided with the Arduino IDE 1.0.1

I've made this work using a static IP address and DNS Server, as in the example sketch.

Is it possible to use DHCP to get a DYNAMIC IP address, while still using a DNS server to resolve a web address ?

The synatax is Ethernet.begin(mac, ip, myDns) for static IP with DNS funtionality.
Just plain Ethernet.begin(mac) for dynamic IP with NO DNS functionality.
I tried Ethernet.begin(mac, , myDNS), but that didn't work.

What I'm trying to do is to get a DYNAMIC IP address yet retain DNS funtionality.

Thank you for helping me.

Bob W

2

Yes. I use it. Call the Ethernet.begin(mac) function. The dhcp server will issue the dns server.

edit: If you want to see what was issued, add this after the Ethernet.begin(mac) call.

Serial.print("ip = ");
Serial.println(Ethernet.localIP());
Serial.print("subnet mask = ");
Serial.println(Ethernet.subnetMask());
Serial.print("gateway = ");
Serial.println(Ethernet.gatewayIP());
Serial.print("dns = ");
Serial.println(Ethernet.dnsServerIP());
3

SurferTim:
Yes. I use it. Call the Ethernet.begin(mac) function. The dhcp server will issue the dns server.

Tim:

Thank you so much!
That was shockingly easy !
Works great !

How did you know this ?
It was hiding in plain sight.
I never thought to try it.

Bob W

4

Hi Bob. Every time a new IDE version is released, I dig through the ethernet library to see what they have added. Just a bit of "code mining". :smiley: