diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index b2422d6015..b4b0087dc0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -685,6 +685,9 @@ Release 2.7.0 - UNRELEASED
HDFS-7308. Change the packet chunk size computation in DFSOutputStream in
order to enforce packet size <= 64kB. (Takuya Fukudome via szetszwo)
+ HDFS-7685. Document dfs.namenode.heartbeat.recheck-interval in
+ hdfs-default.xml. (Kai Sasaki via aajisaka)
+
OPTIMIZATIONS
HDFS-7454. Reduce memory footprint for AclEntries in NameNode.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml b/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
index 85d2273ea3..66fe86c56e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
@@ -144,6 +144,17 @@
+
+ dfs.namenode.heartbeat.recheck-interval
+ 300000
+
+ This time decides the interval to check for expired datanodes.
+ With this value and dfs.heartbeat.interval, the interval of
+ deciding the datanode is stale or not is also calculated.
+ The unit of this configuration is millisecond.
+
+
+
dfs.http.policy
HTTP_ONLY