Perform a first query to initiate curl multi
When using curl multi, we populate the multi with handles and then call multi_perform which leads to curl establishing the multi connection and sending tranfers once it is done. This looks satfisfying enough if we don't look at the time values stored by curl in each handles. In this case it appears that all the transfer time are set to the time the curl multi was started meaning that all transfers keep track of the connection time, this is normal for the first transfer but unnecessary for all the following ones. Therefore by sending a first transfer asking for the root NS, it allows to open the connection without populating the resolver cache. And thus keeps the curl timers more accurate.