This is the UdpNtpClient example modified for dhcp and dns NTP server. Let me know if it works for you.
/*
Udp NTP Client with DHCP and dns acquired NTP server IP
Get the time from a Network Time Protocol (NTP) time server
Demonstrates use of UDP sendPacket and ReceivePacket
For more on NTP time servers and the messages needed to communicate with them,
see http://en.wikipedia.org/wiki/Network_Time_Protocol
created 4 Sep 2010
by Michael Margolis
modified 17 Sep 2010
by Tom Igoe
modified 19 Dec 2012
by Tim Dicus
This code is in the public domain.
*/
#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#include <Dns.h>
// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
unsigned int localPort = 8888; // local port to listen for UDP packets
IPAddress timeServer; // pool.ntp.org NTP server
const int NTP_PACKET_SIZE= 48; // NTP time stamp is in the first 48 bytes of the message
byte packetBuffer[ NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets
// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;
char weekday[7][4] = {"THU","FRI","SAT","SUN","MON","TUE","WED"};
void setup()
{
Serial.begin(9600);
// disable SD SPI while starting w5100
pinMode(4,OUTPUT);
digitalWrite(4,HIGH);
Serial.print(F("Starting w5100..."));
if(!Ethernet.begin(mac))
{
Serial.println(F("failed"));
while(1);
}
else {
Serial.println(F("ok"));
Serial.print(F("ip = "));
Serial.println(Ethernet.localIP());
}
Udp.begin(localPort);
DNSClient dns;
dns.begin(Ethernet.dnsServerIP());
if(dns.getHostByName("pool.ntp.org",timeServer)) {
Serial.print(F("NTP server ip :"));
Serial.println(timeServer);
}
else Serial.print(F("dns lookup failed"));
Serial.println(F("Ready"));
}
void loop()
{
sendNTPpacket(timeServer); // send an NTP packet to a time server
// wait to see if a reply is available
delay(1000);
if ( Udp.parsePacket() ) {
// We've received a packet, read the data from it
Udp.read(packetBuffer,NTP_PACKET_SIZE); // read the packet into the buffer
//the timestamp starts at byte 40 of the received packet and is four bytes,
// or two words, long. First, esxtract the two words:
unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
// combine the four bytes (two words) into a long integer
// this is NTP time (seconds since Jan 1 1900):
Serial.print(packetBuffer[40],DEC);
Serial.print(" ");
Serial.print(packetBuffer[41],DEC);
Serial.print(" ");
Serial.print(packetBuffer[42],DEC);
Serial.print(" ");
Serial.println(packetBuffer[43],DEC);
unsigned long secsSince1900 = highWord << 16 | lowWord;
Serial.print(F("Seconds since Jan 1 1900 = " ));
Serial.println(secsSince1900);
// now convert NTP time into everyday time:
Serial.print(F("Unix time = "));
// Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
const unsigned long seventyYears = 2208988800UL;
// subtract seventy years:
unsigned long epoch = secsSince1900 - seventyYears;
// print Unix time:
Serial.println(epoch);
unsigned long dayCount = epoch / 86400UL;
Serial.print(F("DayCount = "));
Serial.println(dayCount);
Serial.print(F("Day of week = "));
Serial.println(weekday[dayCount%7UL]);
// print the hour, minute and second:
Serial.print(F("The UTC time is ")); // UTC is the time at Greenwich Meridian (GMT)
Serial.print((epoch % 86400L) / 3600); // print the hour (86400 equals secs per day)
Serial.print(':');
if ( ((epoch % 3600) / 60) < 10 ) {
// In the first 10 minutes of each hour, we'll want a leading '0'
Serial.print('0');
}
Serial.print((epoch % 3600) / 60); // print the minute (3600 equals secs per minute)
Serial.print(':');
if ( (epoch % 60) < 10 ) {
// In the first 10 seconds of each minute, we'll want a leading '0'
Serial.print('0');
}
Serial.println(epoch %60); // print the second
}
// wait another 599 seconds (one second delay was above) 10 minutes
for(int y=0;y<599;y++)
{
// count off the minutes
if(y%60 == 0) Serial.println(y/60);
delay(1000);
}
Serial.println();
}
// send an NTP request to the time server at the given address
unsigned long sendNTPpacket(IPAddress& address)
{
// set all bytes in the buffer to 0
memset(packetBuffer, 0, NTP_PACKET_SIZE);
// Initialize values needed to form NTP request
// (see URL above for details on the packets)
packetBuffer[0] = 0b11100011; // LI, Version, Mode
packetBuffer[1] = 0; // Stratum, or type of clock
packetBuffer[2] = 6; // Polling Interval
packetBuffer[3] = 0xEC; // Peer Clock Precision
// 8 bytes of zero for Root Delay & Root Dispersion
packetBuffer[12] = 49;
packetBuffer[13] = 0x4E;
packetBuffer[14] = 49;
packetBuffer[15] = 52;
// all NTP fields have been given values, now
// you can send a packet requesting a timestamp:
Udp.beginPacket(address, 123); //NTP requests are to port 123
Udp.write(packetBuffer,NTP_PACKET_SIZE);
Udp.endPacket();
}
edit: Corrected time delay loop again. It counts off the minutes and checks time every 10 minutes (was 1 minute). I was on to the second after 10 minutes.