DNS Slave Zone Transfers

[Arthur D'Alessandro]

Whenever I delete all the zone files, from my slave nameserver, and reload
it, whether it be from ndc or from kill -hup PID, can someone explain?  I
have this directory structure:
directory : /usr/named
with my zone files for the slave in /usr/named/slave
so I have as
zone "xxx.com" {
    file "slave/xxx.xcom.zone";
which works, and the zone files are created as neccessary, but the below
files appear in my /usr/named direcotry.  Any ideas please?

-rw-r--r--   1 root     other        248 Jun 26 17:01 xfer.ddt.03aWqd
-rw-r--r--   1 root     other        269 Jun 26 17:01 xfer.ddt.2BaWud
-rw-r--r--   1 root     other        262 Jun 26 17:01 xfer.ddt.35aiud
-rw-r--r--   1 root     other        309 Jun 26 17:01 xfer.ddt.37aGtd
-rw-r--r--   1 root     other        244 Jun 26 17:01 xfer.ddt.4_ayrd
-rw-r--r--   1 root     other        284 Jun 26 17:01 xfer.ddt.58aWsd
-rw-r--r--   1 root     other        248 Jun 26 17:01 xfer.ddt.5Ha4td
-rw-r--r--   1 root     other        255 Jun 26 17:01 xfer.ddt.E.aasd
-rw-r--r--   1 root     other        255 Jun 26 17:01 xfer.ddt.Gjaqud
-rw-r--r--   1 root     other        284 Jun 26 17:01 xfer.ddt.HpaGrd
-rw-r--r--   1 root     other        308 Jun 26 17:01 xfer.ddt.JraWrd
-rw-r--r--   1 root     other        309 Jun 26 17:01 xfer.ddt.K6aard
-rw-r--r--   1 root     other        293 Jun 26 17:01 xfer.ddt.NCa4ud
-rw-r--r--   1 root     other        262 Jun 26 17:01 xfer.ddt.NDaysd
-rw-r--r--   1 root     other        244 Jun 26 17:01 xfer.ddt.Nmaitd
-rw-r--r--   1 root     other        248 Jun 26 17:01 xfer.ddt.Q2aOqd
-rw-r--r--   1 root     other        284 Jun 26 17:01 xfer.ddt.VAaOtd
-rw-r--r--   1 root     other        273 Jun 26 17:01 xfer.ddt.VTaOsd
-rw-r--r--   1 root     other        260 Jun 26 17:01 xfer.ddt.VzaOud
-rw-r--r--   1 root     other        253 Jun 26 17:01 xfer.ddt.ZCaWtd
-rw-r--r--   1 root     other        241 Jun 26 17:01 xfer.ddt._naqsd
-rw-r--r--   1 root     other        309 Jun 26 17:01 xfer.ddt._paOrd
-rw-r--r--   1 root     other        304 Jun 26 17:01 xfer.ddt.b6a4qd
-rw-r--r--   1 root     other        293 Jun 26 17:01 xfer.ddt.hCaqtd
-rw-r--r--   1 root     other        255 Jun 26 17:01 xfer.ddt.hFa4rd
-rw-r--r--   1 root     other        288 Jun 26 17:01 xfer.ddt.h_aisd
-rw-r--r--   1 root     other        272 Jun 26 17:01 xfer.ddt.hkayud
-rw-r--r--   1 root     other        255 Jun 26 17:01 xfer.ddt.mzaGud
-rw-r--r--   1 root     other        248 Jun 26 17:01 xfer.ddt.pQaaud
-rw-r--r--   1 root     other        293 Jun 26 17:01 xfer.ddt.qTaGsd
-rw-r--r--   1 root     other        308 Jun 26 17:01 xfer.ddt.x9a4sd
-rw-r--r--   1 root     other        258 Jun 26 17:01 xfer.ddt.y7aytd
-rw-r--r--   1 root     other        255 Jun 26 17:01 xfer.ddt.z_aatd