Responder not Responding

[z0kk]

So I'm pretty new to Responder and I have what very well may be a silly question. I run Responder.py -I ens192, which enables the LLMNR, NBT-NS, and DMS/MDNS poisoners and all of the default servers, including smb.

If I browse from my desktop (same subnet as Responder) directly to the responder server (e.g. \\actual_hostname\anything), responder grabs the hash. If I browse from my desktop to a fake host (\\fakehost\anything), responder doesn't do anything. However, as soon as I try browsing to the fake hostname, tcpdump running on the responder server shows three packets hitting the responder host from my desktop:

11:50:38.811772 IP 192.168.56.240.137 > 192.168.56.255.137: UDP, length 50
11:50:39.563543 IP 192.168.56.240.137 > 192.168.56.255.137: UDP, length 50
11:50:40.325680 IP 192.168.56.240.137 > 192.168.56.255.137: UDP, length 50

If I'm not mistaken, that's netbios name resolution traffic. So my question is why Responder doesn't...like...respond.