diff --git a/scrapy/settings/default_settings.py b/scrapy/settings/default_settings.py
index fb2a58959..0598d5948 100644
--- a/scrapy/settings/default_settings.py
+++ b/scrapy/settings/default_settings.py
@@ -43,9 +43,11 @@ __all__ = [
     "CLOSESPIDER_TIMEOUT_NO_ITEM",
     "COMMANDS_MODULE",
     "COMPRESSION_ENABLED",
+    "CONCURRENT_CONNECTIONS_PER_HANDLER",
     "CONCURRENT_ITEMS",
     "CONCURRENT_REQUESTS",
     "CONCURRENT_REQUESTS_PER_DOMAIN",
+    "CONNECTION_KEEPALIVE_TIMEOUT",
     "COOKIES_DEBUG",
     "COOKIES_ENABLED",
     "CRAWLSPIDER_FOLLOW_LINKS",
diff --git a/tests/test_settings/__init__.py b/tests/test_settings/__init__.py
index 97c095ae0..88622ddac 100644
--- a/tests/test_settings/__init__.py
+++ b/tests/test_settings/__init__.py
@@ -758,6 +758,15 @@ def test_remove_from_list(before, name, item, after):
     assert settings.getpriority(name) == expected_settings.getpriority(name)
 
 
+def test_default_settings_all():
+    deprecated = {"DNS_RESOLVER"}
+    assert scrapy_default_settings.__all__ == sorted(
+        name
+        for name in vars(scrapy_default_settings)
+        if name.isupper() and name not in deprecated
+    )
+
+
 def test_deprecated_dns_resolver_setting():
     settings = Settings()
     with pytest.warns(