diff --git a/bin/tests/system/legacy/clean.sh b/bin/tests/system/legacy/clean.sh
index ad7ef8540d..f883185746 100644
--- a/bin/tests/system/legacy/clean.sh
+++ b/bin/tests/system/legacy/clean.sh
@@ -14,6 +14,7 @@ rm -f ns*/named.run
 rm -f ns*/named.lock
 
 # build.sh
+rm -f ns1/named_dump.db*
 rm -f ns6/K*
 rm -f ns6/dsset-*
 rm -f ns6/edns512.db
diff --git a/bin/tests/system/unknown/tests.sh b/bin/tests/system/unknown/tests.sh
index 190b84020d..eeb8920ffa 100644
--- a/bin/tests/system/unknown/tests.sh
+++ b/bin/tests/system/unknown/tests.sh
@@ -122,16 +122,24 @@ do
 done
 
 echo_i "checking large unknown record loading on master"
-ret=0
-$DIG $DIGOPTS @10.53.0.1 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
-$DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+for try in 0 1 2 3 4 5 6 7 8 9; do
+    ret=0
+    $DIG $DIGOPTS @10.53.0.1 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
+    $DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+    [ "$ret" -eq 0 ] && break
+    sleep 1
+done
 [ $ret = 0 ] || echo_i "failed"
 status=`expr $status + $ret`
 
 echo_i "checking large unknown record loading on slave"
-ret=0
-$DIG $DIGOPTS @10.53.0.2 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
-$DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+for try in 0 1 2 3 4 5 6 7 8 9; do
+    ret=0
+    $DIG $DIGOPTS @10.53.0.2 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
+    $DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+    [ "$ret" -eq 0 ] && break
+    sleep 1
+done
 [ $ret = 0 ] || echo_i "failed"
 status=`expr $status + $ret`
 
@@ -139,10 +147,16 @@ echo_i "stop and restart slave"
 $PERL $SYSTEMTESTTOP/stop.pl unknown ns2
 $PERL $SYSTEMTESTTOP/start.pl --noclean --restart --port ${PORT} unknown ns2
 
+# server may be answering queries before zones are loaded,
+# so retry a few times if this query fails
 echo_i "checking large unknown record loading on slave"
-ret=0
-$DIG $DIGOPTS @10.53.0.2 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
-$DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+for try in 0 1 2 3 4 5 6 7 8 9; do
+    ret=0
+    $DIG $DIGOPTS @10.53.0.2 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
+    $DIFF -s large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+    [ "$ret" -eq 0 ] && break
+    sleep 1
+done
 [ $ret = 0 ] || echo_i "failed"
 status=`expr $status + $ret`
 
@@ -157,10 +171,16 @@ echo_i "stop and restart inline slave"
 $PERL $SYSTEMTESTTOP/stop.pl unknown ns3
 $PERL $SYSTEMTESTTOP/start.pl --noclean --restart --port ${PORT} unknown ns3
 
+# server may be answering queries before zones are loaded,
+# so retry a few times if this query fails
 echo_i "checking large unknown record loading on inline slave"
-ret=0
-$DIG $DIGOPTS @10.53.0.3 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
-$DIFF large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+for try in 0 1 2 3 4 5 6 7 8 9; do
+    ret=0
+    $DIG $DIGOPTS @10.53.0.3 +tcp +short large.example TYPE45234 > dig.out || { ret=1 ; echo_i "dig failed" ; }
+    $DIFF large.out dig.out > /dev/null || { ret=1 ; echo_i "$DIFF failed"; }
+    [ "$ret" -eq 0 ] && break
+    sleep 1
+done
 [ $ret = 0 ] || echo_i "failed"
 status=`expr $status + $ret`
 
diff --git a/bin/tests/system/xfer/tests.sh b/bin/tests/system/xfer/tests.sh
index 8f489f8336..13fc762c4a 100755
--- a/bin/tests/system/xfer/tests.sh
+++ b/bin/tests/system/xfer/tests.sh
@@ -431,12 +431,17 @@ $DIG -p ${PORT} txt mapped @10.53.0.3 > dig.out.1.$n
 grep "status: NOERROR," dig.out.1.$n > /dev/null || tmp=1
 $PERL $SYSTEMTESTTOP/stop.pl xfer ns3
 $PERL $SYSTEMTESTTOP/start.pl --noclean --restart --port ${PORT} xfer ns3
-sleep 1
-$DIG -p ${PORT} txt mapped @10.53.0.3 > dig.out.2.$n
-grep "status: NOERROR," dig.out.2.$n > /dev/null || tmp=1
-$DIG -p ${PORT} axfr mapped @10.53.0.3 > dig.out.3.$n
-digcomp knowngood.mapped dig.out.3.$n || tmp=1
-if test $tmp != 0 ; then echo_i "failed"; fi
+for try in 0 1 2 3 4 5 6 7 8 9; do
+    iret=0
+    $DIG -p ${PORT} txt mapped @10.53.0.3 > dig.out.2.$n
+    grep "status: NOERROR," dig.out.2.$n > /dev/null || iret=1
+    $DIG -p ${PORT} axfr mapped @10.53.0.3 > dig.out.3.$n
+    digcomp knowngood.mapped dig.out.3.$n || iret=1
+    [ "$iret" -eq 0 ] && break
+    sleep 1
+done
+[ "$iret" -eq 0 ] || tmp=1
+[ "$tmp" -ne 0 ] && echo_i "failed"
 status=`expr $status + $tmp`
 
 n=`expr $n + 1`