Funcionando bem do meu lado ... talvez algo do seu lado esteja errado, ou você tentou fazer o ping antes que os registros DNS que você adicionou propagassem?
C:\Users\user>nslookup onebyinfinity.co.nz
Server: DD-WRT
Address: 192.168.1.1
Non-authoritative answer:
Name: onebyinfinity.co.nz
Address: 203.124.98.229
C:\Users\user>ping onebyinfinity.co.nz
Pinging onebyinfinity.co.nz [203.124.98.229] with 32 bytes of data:
Reply from 203.124.98.229: bytes=32 time=275ms TTL=114
Reply from 203.124.98.229: bytes=32 time=265ms TTL=114
Reply from 203.124.98.229: bytes=32 time=262ms TTL=114
Reply from 203.124.98.229: bytes=32 time=262ms TTL=114
Ping statistics for 203.124.98.229:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 262ms, Maximum = 275ms, Average = 266ms
C:\Users\user>ping 203.124.98.229
Pinging 203.124.98.229 with 32 bytes of data:
Reply from 203.124.98.229: bytes=32 time=265ms TTL=114
Reply from 203.124.98.229: bytes=32 time=266ms TTL=114
Reply from 203.124.98.229: bytes=32 time=259ms TTL=114
Reply from 203.124.98.229: bytes=32 time=259ms TTL=114
Ping statistics for 203.124.98.229:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 259ms, Maximum = 266ms, Average = 262ms
C:\Users\user>