diff --git a/CHANGES/11293.misc.rst b/CHANGES/11293.misc.rst
new file mode 100644
index 00000000000..d0b87fe2317
--- /dev/null
+++ b/CHANGES/11293.misc.rst
@@ -0,0 +1,4 @@
+Fixed flaky ``test_aiohttp_request_ctx_manager_not_found`` by switching the
+unresolvable hostname to use the reserved ``.invalid`` TLD (RFC 2606), which is
+guaranteed not to resolve, instead of relying on a real domain that could be
+hijacked or unexpectedly resolved by some networks -- by :user:`copilot`.
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index 51dfc6d44c9..e77c1feb6ea 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -3753,9 +3753,13 @@ async def handler(request: web.Request) -> NoReturn:
 
 
 async def test_aiohttp_request_ctx_manager_not_found() -> None:
+    # Use the reserved ``.invalid`` TLD (RFC 2606) so DNS resolution is
+    # guaranteed to fail, instead of relying on a real domain name which
+    # may unexpectedly resolve on some networks (e.g. ISP NXDOMAIN
+    # hijacking) and make this test flaky. See #11293.
     with pytest.raises(aiohttp.ClientConnectionError):
-        async with aiohttp.request("GET", "http://wrong-dns-name.com"):
-            assert False
+        async with aiohttp.request("GET", "http://wrong-dns-name.invalid"):
+            assert False, "never executed"
 
 
 async def test_raising_client_connector_dns_error_on_dns_failure() -> None: