Well it looks like ns1.healthalliance.co.nz is down.
dig www.healthalliance.co.nz @210.54.1.142 works
dig www.healthalliance.co.nz @210.54.1.143 fails.
given the the reverse DNS for 210.54.1.143 and 210.54.1.142 is also
on those servers, you're going to get timeouts galore.
ns1.healthalliance.co.nz. 86400 IN A 210.54.1.143
ns2.healthalliance.co.nz. 86400 IN A 210.54.1.142
jfp.
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Jean-Francois Pirus