Since Bitcoin Core 0.14.0, how does a node with default settings compute the dust limit?
The dust limit in 0.14.0+ is set by a value called the dustRelayFee. This is separate from the minRelayTxFee although it has the same default value of 1 satoshi/byte. That is what is used to calculate dust now, and the dust calculation is still the same as before. So the default dust limit in 0.14.0+ is 546 satoshis. You can configure the value you set for the dustRelayFee by using the -dustrelayfee=&lt;n&gt; option.

In Bitcoin Core 0.15.0, this will change slightly. The calculation changes to be that the dust limit is the amount that we would pay to spend the output at the dustRelayFee. To keep the dust limit the same as before at 546 satoshis, the dustRelayFee is increased to 3 satoshis/byte.