knsupdate udp timeout until all slave timeout

my knot.conf

system {
        rundir "/var/run/knot";
}

interfaces {
        local_ipv4 { address 0.0.0.0@53; }
}

control {
        listen-on "knot.sock";
}

log {
  file "/var/log/knotd.debug" {
    server debug;
   }

  file "/var/log/knot.log" {
   zone debug;
  }
}


remotes {
  include "remotes.conf"
}

zones {

  storage "/etc/knot/zones";
  zonefile-sync 0;
  include "zones.conf";
  ixfr-from-differences on;
  notify-timeout 60;
  notify-retries 5;
  serial-policy unixtime;
}

remotes.conf

update624db129b32c21fb { address 127.0.0.1@53; }

slave02c4da8e55c06c68 { address 103.26.0.64@53; }

slave03c4da8e55c06c68 { address 103.26.0.65@53; }

slave04c4da8e55c06c68 { address 202.106.0.218@53; }

slave05c4da8e55c06c68 { address 114.234.22.6@53; }

zones.conf

ugametool.com {
  file "ugametool.com";
  xfr-out slave02c4da8e55c06c68;
  notify-out slave02c4da8e55c06c68;
  notify-out slave03c4da8e55c06c68;
  notify-out slave04c4da8e55c06c68;
  notify-out slave05c4da8e55c06c68;
  update-in update624db129b32c21fb;
}

update-add.txt

server 127.0.0.1
zone ugametool.com.
origin ugametool.com.
ttl 36
add baiiiiidu11.ugametool.com. 35 A 192.168.2.2
show
send

run command

/etc/init.d/knot restart
knsupdate  ./update-add.txt

knot.log is fllow

[root@CDN-TOP-Layer ~]# cat /var/log/knot.log 2015-06-23T09:51:57 info: [ugametool.com] zone will be loaded, serial 0 2015-06-23T09:51:57 info: [ugametool.com] loaded, serial 0 -> 1434704091 2015-06-23T09:51:57 info: [ugametool.com] NOTIFY, outgoing, 103.26.0.64@53: serial 1434704091 2015-06-23T09:51:57 warning: [ugametool.com] NOTIFY, outgoing, 103.26.0.65@53: failed (connection refused) 2015/6/23-9:51:57.84 103.26.0.64 ugametool.com. IN SOA 2015/6/23-9:51:59.89 127.0.0.1 ugametool.com. IN SOA 2015/6/23-9:52:2.89 127.0.0.1 ugametool.com. IN SOA 2015/6/23-9:52:5.90 127.0.0.1 ugametool.com. IN SOA 2015-06-23T09:52:07 warning: [ugametool.com] NOTIFY, outgoing, 202.106.0.218@53: failed (connection timeout) 2015/6/23-9:52:8.90 127.0.0.1 ugametool.com. IN SOA 2015-06-23T09:52:17 warning: [ugametool.com] NOTIFY, outgoing, 114.234.22.6@53: failed (connection timeout) 2015-06-23T09:52:17 info: [ugametool.com] DDNS, processing 4 updates 2015-06-23T09:52:17 info: [ugametool.com] DDNS, finished, no changes to the zone were made