diff --git a/bin/tests/system/kasp/tests.sh b/bin/tests/system/kasp/tests.sh
index 650c961f4e..8856e2db7d 100644
--- a/bin/tests/system/kasp/tests.sh
+++ b/bin/tests/system/kasp/tests.sh
@@ -4660,6 +4660,17 @@ dnssec_verify
 # an unlimited lifetime.  Fallback to the default loadkeys interval.
 check_next_key_event 3600
 
+_check_soa_ttl() {
+	dig_with_opts @10.53.0.6 example SOA > dig.out.ns6.test$n.soa2 || return 1
+	soa1=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa1)
+	soa2=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa2)
+	ttl1=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa1)
+	ttl2=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa2)
+	test ${soa1:-1000} -lt ${soa2:-0} || return 1
+	test ${ttl1:-0} -eq $1 || return 1
+	test ${ttl2:-0} -eq $2 || return 1
+}
+
 echo_i "Check that 'rndc reload' of just the serial updates the signed instance ($n)"
 TSIG=
 ret=0
@@ -4668,15 +4679,9 @@ cp ns6/example2.db.in ns6/example.db || ret=1
 nextpart ns6/named.run > /dev/null
 rndccmd 10.53.0.6 reload || ret=1
 wait_for_log 3 "all zones loaded" ns6/named.run
-sleep 1
-dig_with_opts @10.53.0.6 example SOA > dig.out.ns6.test$n.soa2 || ret=1
-soa1=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa1)
-soa2=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa2)
-ttl1=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa1)
-ttl2=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa2)
-test ${soa1:-1000} -lt ${soa2:-0} || ret=1
-test ${ttl1:-0} -eq 300 || ret=1
-test ${ttl2:-0} -eq 300 || ret=1
+# Check that the SOA SERIAL increases and check the TTLs (should be 300 as
+# defined in ns6/example2.db.in).
+retry_quiet 10 _check_soa_ttl 300 300 || ret=1
 test "$ret" -eq 0 || echo_i "failed"
 status=$((status+ret))
 n=$((n+1))
@@ -4692,15 +4697,9 @@ rm ns6/example.db.jnl
 nextpart ns6/named.run > /dev/null
 start_server --noclean --restart --port ${PORT} kasp ns6
 wait_for_log 3 "all zones loaded" ns6/named.run
-sleep 1
-dig_with_opts @10.53.0.6 example SOA > dig.out.ns6.test$n.soa2 || ret=1
-soa1=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa1)
-soa2=$(awk '$4 == "SOA" { print $7 }' dig.out.ns6.test$n.soa2)
-ttl1=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa1)
-ttl2=$(awk '$4 == "SOA" { print $2 }' dig.out.ns6.test$n.soa2)
-test ${soa1:-1000} -lt ${soa2:-0} || ret=1
-test ${ttl1:-0} -eq 300 || ret=1
-test ${ttl2:-0} -eq 400 || ret=1
+# Check that the SOA SERIAL increases and check the TTLs (should be changed
+# from 300 to 400 as defined in ns6/example3.db.in).
+retry_quiet 10 _check_soa_ttl 300 400 || ret=1
 test "$ret" -eq 0 || echo_i "failed"
 status=$((status+ret))
 n=$((n+1))