PHP json a id

echo $obj->probes->id->28->name;

{"probes":[{"id":28,"country":"Netherlands","city":"Amsterdam","name":"Amsterdam 2, Netherlands","active":true,"hostname":"s406.zzz.com","ip":"a","countryiso":"NL"},{"id":32,"country":"United States","city":"Los Angeles","name":"Los Angeles, CA","active":true,"hostname":"s410.zzz.com","ip":"b","countryiso":"US"},{"id":33,"country":"France","city":"Strasbourg","name":"Strasbourg, France","active":true,"hostname":"s411.zzz.com","ip":"xxx","countryiso":"FR"} ....

<?php
$json = '{"probes":[{"id":28,"country":"Netherlands","city":"Amsterdam","name":"Amsterdam 2, Netherlands","active":true,"hostname":"s406.zzz.com","ip":"a","countryiso":"NL"},{"id":32,"country":"United States","city":"Los Angeles","name":"Los Angeles, CA","active":true,"hostname":"s410.zzz.com","ip":"b","countryiso":"US"},{"id":33,"country":"France","city":"Strasbourg","name":"Strasbourg, France","active":true,"hostname":"s411.zzz.com","ip":"xxx","countryiso":"FR"}]}';
$obj  = json_decode($json);
echo    $obj->probes->id->33->name;