diff --git a/roles/mirrormanager/backend/files/backend.cron b/roles/mirrormanager/backend/files/backend.cron
index 35ca9fe442..fd3a15bd54 100644
--- a/roles/mirrormanager/backend/files/backend.cron
+++ b/roles/mirrormanager/backend/files/backend.cron
@@ -18,8 +18,8 @@ MAILTO=root
 15 */2 * * * mirrormanager /usr/local/bin/umdl-required archive /var/log/mirrormanager/umdl-required.log
 45 */2  * * * mirrormanager /usr/local/bin/umdl-required alt /var/log/mirrormanager/umdl-required.log
 
-# check if category CentOS needs updating every two hours
-33 */2 * * * mirrormanager /usr/local/bin/umdl-required centos /var/log/mirrormanager/umdl-required.log
+# check if category CentOS needs updating every 15 minutes
+57,12,27,42 * * * * mirrormanager /usr/local/bin/umdl-required centos /var/log/mirrormanager/umdl-required.log
 
 # Sync netblocks list once a day
 30 0 * * * mirrormanager cd /usr/share/mirrormanager2 && /usr/bin/mm2_get_global_netblocks /var/lib/mirrormanager/global_netblocks.txt
diff --git a/roles/mirrormanager/backend/files/umdl-required b/roles/mirrormanager/backend/files/umdl-required
index 7af8c7d1b1..a57b042f06 100644
--- a/roles/mirrormanager/backend/files/umdl-required
+++ b/roles/mirrormanager/backend/files/umdl-required
@@ -46,9 +46,17 @@ else
 fi
 
 if [ "${1}" ==  "centos" ]; then
-	FFTL="http://centos-master01.iad2.fedoraproject.org/9-stream/COMPOSE_ID"
+	CENTOS_PRIMARY="mref1-priv.iad2.centos.org"
+	# check if a sync is currently in process
+	CODE=$( curl -s -o /dev/null -I -w "%{http_code}" http://${CENTOS_PRIMARY}/9-stream/.sync_in_progress )
+	if [ "${CODE}" -eq "200" ]; then
+		echo -n "CentOS primary mirror sync in progress. Skipping scan at "
+		date
+		exit 0
+	fi
+	FFTL="http://${CENTOS_PRIMARY}/9-stream/COMPOSE_ID"
 	FILEDATE=`date +%s -d"$( curl -s --head ${FFTL} | awk 'BEGIN {FS=": "}/^Last-Modified/{print $2}' )"`
-	FFTL_SIGS="http://centos-master01.iad2.fedoraproject.org/SIGs/9-stream/COMPOSE_ID"
+	FFTL_SIGS="http://${CENTOS_PRIMARY}/SIGs/9-stream/COMPOSE_ID"
 	FILEDATE_SIGS=`date +%s -d"$( curl -s --head ${FFTL_SIGS} | awk 'BEGIN {FS=": "}/^Last-Modified/{print $2}' )"`
 	if [ "$FILEDATE_SIGS" -gt "$FILEDATE" ]; then
 		FILEDATE=$FILEDATE_SIGS