The following command modifies the cluster check type:

curl -k "https://bal:1fourall@20.200.25.100/access/modcluster?ip=3.3.3.3&checker=icmp"

Response: 

<?xml version="1.0" encoding="ISO-8859-1"?>
<Response stat="200" code="ok">
<Success><Data><cluster><Status>Up</Status>
<Index>1</Index>
<Name>addedcluster</Name>
<ClusterVSAddress></ClusterVSAddress><IPAddress>3.3.3.3</IPAddress>

<Checker>icmp</Checker>

<CheckerPort>0</CheckerPort>
<Type>default</Type>
<Enable>Y</Enable>
<LocationLatitude>0.00000000</LocationLatitude>
<LocationLongitude>0.00000000</LocationLongitude>
</cluster></Data>
</Success>
</Response>