mknod to create /dev/null equivalent not working

[James E. Pace]

After "mknod /foo/dev/null c 0 0x1b":

$ \ls -l /dev/null /foo/dev/null
crw-rw-rw-  1 root  wheel  0x1b Aug 28 15:34 /foo/dev/null
crw-rw-rw-  1 root  wheel  0x1b Aug 28 15:36 /dev/null
$ cat /etc/hosts > /dev/null
$ cat /etc/hosts > /foo/dev/null
/foo/dev/null: Operation not supported.

What am I doing wrong?  Why isn't the device I created acting like
/dev/null?

Tried on FreeBSD 11.1.

Thanks,

James
-- 
James E. Pace