When you send Tx hash to them, they never come back to you for the Tx detail.
Have you tried to send tx with non-dust amount and reasonable fee
only to these nodes?
Was it mined in reasonable time?
Is there any thing special that nodes like these are made for?
Bitcoin network traffic sniffing & analyzing. Usually, there is more than enough to have one node for such work.
Wondering why do they have several IP addresses.