pfSense

Some not-particularly-well-behaved DHCP clients put spaces in the hostname. For example:

lease xx.xx.32.103 {
  starts 5 2019/09/13 12:40:41;
  ends 5 2019/09/13 14:40:41;
  cltt 5 2019/09/13 12:40:41;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 40:d2:8a:xx:xx:xx;
  uid "\001@\322\212\261\223\271";
  client-hostname "Nintendo 3DS";
}
lease xx.xx.32.103 {
  starts 5 2019/09/13 12:40:41;
  ends 5 2019/09/13 12:40:55;
  tstp 5 2019/09/13 12:40:55;
  cltt 5 2019/09/13 12:40:41;
  binding state free;
  hardware ethernet 40:d2:8a:xx:xx:xx;
  uid "\001@\322\212\261\223\271";
}

The GUI handling of these was addressed in #3500, but dhcpleases is only using the first word of the hostname:

: grep -i nintendo /var/unbound/dhcpleases_entries.conf 
local-data: "Nintendo.xxxxxx.org IN A xx.xx.32.103" 
local-data-ptr: "xx.xx.32.103 Nintendo.xxxxxx.org" 

In this case, the space should probably be removed or replaced by another character valid for hostnames in DNS, such as -.