diff --git a/doc/api/net.md b/doc/api/net.md
index f8cd3ccf8d3c40..c6321c3b38c7a7 100644
--- a/doc/api/net.md
+++ b/doc/api/net.md
@@ -1402,6 +1402,9 @@ data packet received and the first keepalive probe. Setting `0` for
 `initialDelay` will leave the value unchanged from the default
 (or previous) setting.
 
+**Note:** Node.js converts `initialDelay` from milliseconds to seconds and truncates any fractional part.
+For example, `1500` becomes `1`, and values from `1` to `999` become `0`.
+
 Enabling the keep-alive functionality will set the following socket options:
 
 * `SO_KEEPALIVE=1`