Verify DNS fallback for configured contact endpoints

tests/unit/test_async_manager.py

@@ -202,6 +202,29 @@ async def mock_fetch(url: str) -> list[str]:
 
         assert manager.next_node_uri() == "http://[2001:db8::2]:8000"
 
+    @pytest.mark.asyncio
+    async def test_refresh_recovers_through_original_dns_entrypoint(self) -> None:
+        """Later async refreshes keep using the original contact hostname."""
+        config = Config(seed_hosts=["entrypoint.test"], port=8000)
+        calls: list[str] = []
+
+        async def mock_fetch(url: str) -> list[str]:
+            calls.append(url)
+            if len(calls) == 1:
+                return ["old-node.test"]
+            return ["new-node.test"]
+
+        manager = AsyncLiveNodesManager(config, mock_fetch)
+
+        assert await manager.refresh_nodes() is True
+        assert manager.nodes.nodes == ("old-node.test",)
+        assert await manager.refresh_nodes() is True
+        assert manager.nodes.nodes == ("new-node.test",)
+        assert calls == [
+            "http://entrypoint.test:8000/localnodes",
+            "http://entrypoint.test:8000/localnodes",
+        ]
+
     @pytest.mark.asyncio
     async def test_url_construction_with_dc_scope(self, config: Config) -> None:
         """Test URL construction with datacenter scope."""

tests/unit/test_http.py

@@ -424,6 +424,47 @@ def test_session_cache_disabled(self) -> None:
         assert context.options & ssl.OP_NO_TICKET
 
 
+@pytest.mark.asyncio
+async def test_async_fetcher_tries_later_dns_address_on_connection_failure() -> None:
+    """Async bootstrap reaches a later address from the resolver answer."""
+    pytest.importorskip("aiohttp")
+    MockHTTPHandler.response_data = ["127.0.0.1"]
+    MockHTTPHandler.response_code = 200
+    server = HTTPServer(("127.0.0.1", 0), MockHTTPHandler)
+    thread = Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    records = [
+        (
+            socket.AF_INET,
+            socket.SOCK_STREAM,
+            socket.IPPROTO_TCP,
+            "",
+            ("127.0.0.2", server.server_port),
+        ),
+        (
+            socket.AF_INET,
+            socket.SOCK_STREAM,
+            socket.IPPROTO_TCP,
+            "",
+            ("127.0.0.1", server.server_port),
+        ),
+    ]
+    fetcher = AsyncNodeFetcher(timeout_seconds=1.0)
+
+    try:
+        with patch("socket.getaddrinfo", return_value=records):
+            nodes = await fetcher(
+                f"http://entrypoint.test:{server.server_port}/localnodes"
+            )
+    finally:
+        await fetcher.close()
+        server.shutdown()
+        server.server_close()
+        thread.join(timeout=5.0)
+
+    assert list(nodes) == ["127.0.0.1"]
+
+
 @pytest.mark.asyncio
 async def test_async_fetcher_reuses_connection_after_repeated_non_success_responses() -> (
     None