--- loncom/lonnet/perl/lonnet.pm	2018/08/07 17:12:25	1.1380
+++ loncom/lonnet/perl/lonnet.pm	2018/08/18 22:07:59	1.1383
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1380 2018/08/07 17:12:25 raeburn Exp $
+# $Id: lonnet.pm,v 1.1383 2018/08/18 22:07:59 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -230,7 +230,12 @@ sub get_server_distarch {
 }
 
 sub get_servercerts_info {
-    my ($lonhost,$context) = @_;
+    my ($lonhost,$hostname,$context) = @_;
+    return if ($lonhost eq '');
+    if ($hostname eq '') {
+        $hostname = &hostname($lonhost);
+    }
+    return if ($hostname eq '');
     my ($rep,$uselocal);
     if (grep { $_ eq $lonhost } &current_machine_ids()) {
         $uselocal = 1;
@@ -250,16 +255,11 @@ sub get_servercerts_info {
         }
     }
     if ($uselocal) {
-        $rep = LONCAPA::Lond::server_certs(\%perlvar);
+        $rep = LONCAPA::Lond::server_certs(\%perlvar,$lonhost,$hostname);
     } else {
         $rep=&reply('servercerts',$lonhost);
     }
     my ($result,%returnhash);
-    if (defined($lonhost)) {
-        if (!defined(&hostname($lonhost))) {
-            return;
-        }
-    }
     if (($rep=~/^(refused|rejected|error)/) || ($rep eq 'con_lost') ||
         ($rep eq 'unknown_cmd')) {
         $result = $rep;
@@ -10041,12 +10041,25 @@ sub is_course {
     my ($cdom, $cnum) = scalar(@_) == 1 ? 
          ($_[0] =~ /^($match_domain)_($match_courseid)$/)  :  @_;
 
-    return unless $cdom and $cnum;
-
-    my %courses = &courseiddump($cdom, '.', 1, '.', '.', $cnum, undef, undef,
-        '.');
-
-    return unless(exists($courses{$cdom.'_'.$cnum}));
+    return unless (($cdom =~ /^$match_domain$/) && ($cnum =~ /^$match_courseid$/));
+    my $uhome=&homeserver($cnum,$cdom);
+    my $iscourse;
+    if (grep { $_ eq $uhome } current_machine_ids()) {
+        $iscourse = &LONCAPA::Lond::is_course($cdom,$cnum);
+    } else {
+        my $hashid = $cdom.':'.$cnum;
+        ($iscourse,my $cached) = &is_cached_new('iscourse',$hashid);
+        unless (defined($cached)) {
+            my %courses = &courseiddump($cdom, '.', 1, '.', '.',
+                                        $cnum,undef,undef,'.');
+            $iscourse = 0;
+            if (exists($courses{$cdom.'_'.$cnum})) {
+                $iscourse = 1;
+            }
+            &do_cache_new('iscourse',$hashid,$iscourse,3600);
+        }
+    }
+    return unless ($iscourse);
     return wantarray ? ($cdom, $cnum) : $cdom.'_'.$cnum;
 }