diff --git a/Changes b/Changes
index 2eac3689..bcc6ca6e 100644
--- a/Changes
+++ b/Changes
@@ -1,3 +1,9 @@
+2.036001 - TESTING
+
+  [BUG FIXES]
+
+  * #320 DNS subroutines are redefined
+
 2.036001 - 2017-06-22
 
   [BUG FIXES]
diff --git a/MANIFEST b/MANIFEST
index a89e77d2..4758a5db 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -129,6 +129,7 @@ lib/App/Netdisco/Util/Backend.pm
 lib/App/Netdisco/Util/Device.pm
 lib/App/Netdisco/Util/DNS.pm
 lib/App/Netdisco/Util/ExpandParams.pm
+lib/App/Netdisco/Util/FastResolver.pm
 lib/App/Netdisco/Util/Graph.pm
 lib/App/Netdisco/Util/Node.pm
 lib/App/Netdisco/Util/NodeMonitor.pm
diff --git a/bin/netdisco-sshcollector b/bin/netdisco-sshcollector
index 38f016b1..edb44063 100755
--- a/bin/netdisco-sshcollector
+++ b/bin/netdisco-sshcollector
@@ -42,7 +42,7 @@ BEGIN {
 use App::Netdisco;
 use App::Netdisco::Core::Arpnip 'store_arp';
 use App::Netdisco::Util::Node 'check_mac';
-use App::Netdisco::Util::DNS 'hostnames_resolve_async';
+use App::Netdisco::Util::FastResolver 'hostnames_resolve_async';
 use Dancer ':script';
 
 use Data::Printer;
diff --git a/lib/App/Netdisco/Configuration.pm b/lib/App/Netdisco/Configuration.pm
index 441056c2..d32d63d7 100644
--- a/lib/App/Netdisco/Configuration.pm
+++ b/lib/App/Netdisco/Configuration.pm
@@ -66,6 +66,22 @@ if (exists setting('workers')->{interactives}
 setting('dns')->{hosts_file} ||= '/etc/hosts';
 setting('dns')->{no} ||= ['fe80::/64','169.254.0.0/16'];
 
+# load /etc/hosts
+setting('dns')->{'ETCHOSTS'} = {};
+{
+  # AE::DNS::EtcHosts only works for A/AAAA/SRV, but we want PTR.
+  # this loads+parses /etc/hosts file using AE. dirty hack.
+  use AnyEvent::Socket 'format_address';
+  use AnyEvent::DNS::EtcHosts;
+  AnyEvent::DNS::EtcHosts::_load_hosts_unless(sub{},AE::cv);
+  no AnyEvent::DNS::EtcHosts; # unimport
+
+  setting('dns')->{'ETCHOSTS'}->{$_} =
+    [ map { [ $_ ? (format_address $_->[0]) : '' ] }
+          @{ $AnyEvent::DNS::EtcHosts::HOSTS{ $_ } } ]
+    for keys %AnyEvent::DNS::EtcHosts::HOSTS;
+}
+
 # support unordered dictionary as if it were a single item list
 if (ref {} eq ref setting('device_identity')) {
   config->{'device_identity'} = [ setting('device_identity') ];
diff --git a/lib/App/Netdisco/Core/Arpnip.pm b/lib/App/Netdisco/Core/Arpnip.pm
index a0ca5249..b3a82307 100644
--- a/lib/App/Netdisco/Core/Arpnip.pm
+++ b/lib/App/Netdisco/Core/Arpnip.pm
@@ -4,7 +4,7 @@ use Dancer qw/:syntax :script/;
 use Dancer::Plugin::DBIC 'schema';
 
 use App::Netdisco::Util::Node 'check_mac';
-use App::Netdisco::Util::DNS ':all';
+use App::Netdisco::Util::FastResolver 'hostnames_resolve_async';
 use NetAddr::IP::Lite ':lower';
 use Time::HiRes 'gettimeofday';
 use NetAddr::MAC ();
diff --git a/lib/App/Netdisco/Core/Discover.pm b/lib/App/Netdisco/Core/Discover.pm
index dca91119..25e5e0f4 100644
--- a/lib/App/Netdisco/Core/Discover.pm
+++ b/lib/App/Netdisco/Core/Discover.pm
@@ -6,6 +6,7 @@ use Dancer::Plugin::DBIC 'schema';
 use App::Netdisco::Util::Device
   qw/get_device match_devicetype is_discoverable/;
 use App::Netdisco::Util::Permission 'check_acl_only';
+use App::Netdisco::Util::FastResolver 'hostnames_resolve_async';
 use App::Netdisco::Util::DNS ':all';
 use App::Netdisco::JobQueue qw/jq_queued jq_insert/;
 use NetAddr::IP::Lite ':lower';
diff --git a/lib/App/Netdisco/Util/DNS.pm b/lib/App/Netdisco/Util/DNS.pm
index 96f498b0..cd8ed25f 100644
--- a/lib/App/Netdisco/Util/DNS.pm
+++ b/lib/App/Netdisco/Util/DNS.pm
@@ -5,30 +5,13 @@ use warnings;
 use Dancer ':script';
 
 use Net::DNS;
-use AnyEvent::DNS;
 use NetAddr::IP::Lite ':lower';
 
-use App::Netdisco::Util::Permission;
-
 use base 'Exporter';
 our @EXPORT = ();
-our @EXPORT_OK = qw/
-  hostname_from_ip hostnames_resolve_async ipv4_from_hostname
-/;
+our @EXPORT_OK = qw/hostname_from_ip ipv4_from_hostname/;
 our %EXPORT_TAGS = (all => \@EXPORT_OK);
 
-# AE::DNS::EtcHosts only works for A/AAAA/SRV, but we want PTR.
-# this loads+parses /etc/hosts file using AE. dirty hack.
-use AnyEvent::Socket 'format_address';
-use AnyEvent::DNS::EtcHosts;
-AnyEvent::DNS::EtcHosts::_load_hosts_unless(sub{},AE::cv);
-no AnyEvent::DNS::EtcHosts; # unimport
-
-our %HOSTS = ();
-$HOSTS{$_} = [ map { [ $_ ? (format_address $_->[0]) : '' ] }
-                    @{$AnyEvent::DNS::EtcHosts::HOSTS{$_}} ]
-  for keys %AnyEvent::DNS::EtcHosts::HOSTS;
-
 =head1 NAME
 
 App::Netdisco::Util::DNS
@@ -53,10 +36,11 @@ Returns C<undef> if no PTR record exists for the IP.
 sub hostname_from_ip {
   my $ip = shift;
   return unless $ip;
+  my $ETCHOSTS = setting('dns')->{'ETCHOSTS'};
 
   # check /etc/hosts file and short-circuit if found
-  foreach my $name (reverse sort keys %HOSTS) {
-      if ($HOSTS{$name}->[0]->[0] eq $ip) {
+  foreach my $name (reverse sort keys %$ETCHOSTS) {
+      if ($ETCHOSTS->{$name}->[0]->[0] eq $ip) {
           return $name;
       }
   }
@@ -85,10 +69,11 @@ Returns C<undef> if no A record exists for the name.
 sub ipv4_from_hostname {
   my $name = shift;
   return unless $name;
+  my $ETCHOSTS = setting('dns')->{'ETCHOSTS'};
 
   # check /etc/hosts file and short-circuit if found
-  if (exists $HOSTS{$name} and $HOSTS{$name}->[0]->[0]) {
-      my $ip = NetAddr::IP::Lite->new($HOSTS{$name}->[0]->[0]);
+  if (exists $ETCHOSTS->{$name} and $ETCHOSTS->{$name}->[0]->[0]) {
+      my $ip = NetAddr::IP::Lite->new($ETCHOSTS->{$name}->[0]->[0]);
       return $ip->addr if $ip and $ip->bits == 32;
   }
 
@@ -105,63 +90,4 @@ sub ipv4_from_hostname {
   return undef;
 }
 
-=head2 hostnames_resolve_async( \@ips, \@timeouts? )
-
-This method uses a fully asynchronous and high-performance pure-perl stub
-resolver C<AnyEvent::DNS>.
-
-Given a reference to an array of hashes will resolve the C<IPv4> or C<IPv6>
-address in the C<ip>, C<alias>, or C<device> key of each hash into its
-hostname which will be inserted in the C<dns> key of the hash.
-
-Optionally provide a set of timeout values in seconds which is also the
-number of resolver attempts. The default is C<< [2,5,5] >>.
-
-Returns the supplied reference to an array of hashes with dns values for
-addresses which resolved.
-
-=cut
-
-sub hostnames_resolve_async {
-  my ($ips, $timeouts) = @_;
-  return [] unless $ips and ref [] eq ref $ips;
-  $timeouts ||= [2,5,5];
-
-  my $skip = setting('dns')->{'no'};
-  AnyEvent::DNS::resolver->timeout(@$timeouts);
-
-  # Set up the condvar
-  my $done = AE::cv;
-  $done->begin( sub { shift->send } );
-
-  IP: foreach my $hash_ref (@$ips) {
-    my $ip = $hash_ref->{'ip'} || $hash_ref->{'alias'} || $hash_ref->{'device'};
-    next IP if App::Netdisco::Util::Permission::check_acl_no($ip, $skip);
-
-    # check /etc/hosts file and short-circuit if found
-    foreach my $name (reverse sort keys %HOSTS) {
-        if ($HOSTS{$name}->[0]->[0] eq $ip) {
-            $hash_ref->{'dns'} = $name;
-            next IP;
-        }
-    }
-
-    $done->begin;
-    AnyEvent::DNS::reverse_lookup $ip,
-            sub { $hash_ref->{'dns'} = shift; $done->end; };
-  }
-
-  # Decrement the cv counter to cancel out the send declaration
-  $done->end;
-
-  # Wait for the resolver to perform all resolutions
-  $done->recv;
-  
-  # Remove reference to resolver so that we close sockets
-  # and allow return to any instance defaults we have changed
-  undef $AnyEvent::DNS::RESOLVER if $AnyEvent::DNS::RESOLVER;
-
-  return $ips;
-}
-
 1;
diff --git a/lib/App/Netdisco/Util/FastResolver.pm b/lib/App/Netdisco/Util/FastResolver.pm
new file mode 100644
index 00000000..569c7af6
--- /dev/null
+++ b/lib/App/Netdisco/Util/FastResolver.pm
@@ -0,0 +1,88 @@
+package App::Netdisco::Util::FastResolver;
+
+use strict;
+use warnings;
+use Dancer ':script';
+
+use AnyEvent::DNS;
+use App::Netdisco::Util::Permission 'check_acl_no';
+
+use base 'Exporter';
+our @EXPORT = ();
+our @EXPORT_OK = qw/hostnames_resolve_async/;
+our %EXPORT_TAGS = (all => \@EXPORT_OK);
+
+=head1 NAME
+
+App::Netdisco::Util::FastResolver
+
+=head1 DESCRIPTION
+
+A set of helper subroutines to support parts of the Netdisco application.
+
+There are no default exports, however the C<:all> tag will export all
+subroutines.
+
+=head1 EXPORT_OK
+
+=head2 hostnames_resolve_async( \@ips, \@timeouts? )
+
+This method uses a fully asynchronous and high-performance pure-perl stub
+resolver C<AnyEvent::DNS>.
+
+Given a reference to an array of hashes will resolve the C<IPv4> or C<IPv6>
+address in the C<ip>, C<alias>, or C<device> key of each hash into its
+hostname which will be inserted in the C<dns> key of the hash.
+
+Optionally provide a set of timeout values in seconds which is also the
+number of resolver attempts. The default is C<< [2,5,5] >>.
+
+Returns the supplied reference to an array of hashes with dns values for
+addresses which resolved.
+
+=cut
+
+sub hostnames_resolve_async {
+  my ($ips, $timeouts) = @_;
+  return [] unless $ips and ref [] eq ref $ips;
+  $timeouts ||= [2,5,5];
+
+  my $skip = setting('dns')->{'no'};
+  my $ETCHOSTS = setting('dns')->{'ETCHOSTS'};
+  AnyEvent::DNS::resolver->timeout(@$timeouts);
+
+  # Set up the condvar
+  my $done = AE::cv;
+  $done->begin( sub { shift->send } );
+
+  IP: foreach my $hash_ref (@$ips) {
+    my $ip = $hash_ref->{'ip'} || $hash_ref->{'alias'} || $hash_ref->{'device'};
+    next IP if check_acl_no($ip, $skip);
+
+    # check /etc/hosts file and short-circuit if found
+    foreach my $name (reverse sort keys %$ETCHOSTS) {
+        if ($ETCHOSTS->{$name}->[0]->[0] eq $ip) {
+            $hash_ref->{'dns'} = $name;
+            next IP;
+        }
+    }
+
+    $done->begin;
+    AnyEvent::DNS::reverse_lookup $ip,
+            sub { $hash_ref->{'dns'} = shift; $done->end; };
+  }
+
+  # Decrement the cv counter to cancel out the send declaration
+  $done->end;
+
+  # Wait for the resolver to perform all resolutions
+  $done->recv;
+
+  # Remove reference to resolver so that we close sockets
+  # and allow return to any instance defaults we have changed
+  undef $AnyEvent::DNS::RESOLVER if $AnyEvent::DNS::RESOLVER;
+
+  return $ips;
+}
+
+1;
diff --git a/lib/App/Netdisco/Web/Plugin/AdminTask/TimedOutDevices.pm b/lib/App/Netdisco/Web/Plugin/AdminTask/TimedOutDevices.pm
index f7048c1f..23d2dd8b 100644
--- a/lib/App/Netdisco/Web/Plugin/AdminTask/TimedOutDevices.pm
+++ b/lib/App/Netdisco/Web/Plugin/AdminTask/TimedOutDevices.pm
@@ -6,7 +6,7 @@ use Dancer::Plugin::DBIC;
 use Dancer::Plugin::Auth::Extensible;
 
 use App::Netdisco::Web::Plugin;
-use App::Netdisco::Util::DNS 'hostnames_resolve_async';
+use App::Netdisco::Util::FastResolver 'hostnames_resolve_async';
 
 register_admin_task({
   tag => 'timedoutdevices',