diff --git a/plugin/bufsize/README.md b/plugin/bufsize/README.md
index 56a9dddfc..0dc96235c 100644
--- a/plugin/bufsize/README.md
+++ b/plugin/bufsize/README.md
@@ -1,11 +1,15 @@
 # bufsize
 ## Name
-*bufsize* - sizes EDNS0 buffer size to prevent IP fragmentation.
+*bufsize* - limits EDNS0 buffer size to prevent IP fragmentation.
 
 ## Description
-*bufsize* limits a requester's UDP payload size.
+*bufsize* limits a requester's UDP payload size to within a maximum value.
+If a request with an OPT RR has a bufsize greater than the limit, the bufsize
+of the request will be reduced. Otherwise the request is unaffected.
 It prevents IP fragmentation, mitigating certain DNS vulnerabilities.
-This will only affect queries that have an OPT RR.
+It cannot increase UDP size requested by the client, it can be reduced only.
+This will only affect queries that have
+an OPT RR ([EDNS(0)](https://www.rfc-editor.org/rfc/rfc6891)).
 
 ## Syntax
 ```txt
@@ -13,14 +17,14 @@ bufsize [SIZE]
 ```
 
 **[SIZE]** is an int value for setting the buffer size.
-The default value is 512, and the value must be within 512 - 4096.
+The default value is 1232, and the value must be within 512 - 4096.
 Only one argument is acceptable, and it covers both IPv4 and IPv6.
 
 ## Examples
 Enable limiting the buffer size of outgoing query to the resolver (172.31.0.10):
 ```corefile
 . {
-    bufsize 512
+    bufsize 1100
     forward . 172.31.0.10
     log
 }
@@ -29,7 +33,7 @@ Enable limiting the buffer size of outgoing query to the resolver (172.31.0.10):
 Enable limiting the buffer size as an authoritative nameserver:
 ```corefile
 . {
-    bufsize 512
+    bufsize 1220
     file db.example.org
     log
 }
diff --git a/plugin/bufsize/setup.go b/plugin/bufsize/setup.go
index 7ac602d5d..56113e633 100644
--- a/plugin/bufsize/setup.go
+++ b/plugin/bufsize/setup.go
@@ -24,12 +24,13 @@ func setup(c *caddy.Controller) error {
 }
 
 func parse(c *caddy.Controller) (int, error) {
-	const defaultBufSize = 512
+	// value from http://www.dnsflagday.net/2020/
+	const defaultBufSize = 1232
 	for c.Next() {
 		args := c.RemainingArgs()
 		switch len(args) {
 		case 0:
-			// Nothing specified; use 512 as default
+			// Nothing specified; use defaultBufSize
 			return defaultBufSize, nil
 		case 1:
 			// Specified value is needed to verify
diff --git a/plugin/bufsize/setup_test.go b/plugin/bufsize/setup_test.go
index bb103027d..5bf7b8095 100644
--- a/plugin/bufsize/setup_test.go
+++ b/plugin/bufsize/setup_test.go
@@ -14,10 +14,11 @@ func TestSetupBufsize(t *testing.T) {
 		expectedData       int
 		expectedErrContent string // substring from the expected error. Empty for positive cases.
 	}{
-		{`bufsize`, false, 512, ""},
-		{`bufsize "1232"`, false, 1232, ""},
+		{`bufsize`, false, 1232, ""},
+		{`bufsize "1220"`, false, 1220, ""},
 		{`bufsize "5000"`, true, -1, "plugin"},
 		{`bufsize "512 512"`, true, -1, "plugin"},
+		{`bufsize "511"`, true, -1, "plugin"},
 		{`bufsize "abc123"`, true, -1, "plugin"},
 	}