assertEquals(5, poolSpy.failCounts.get("10.0.0.1"));
    }

    @Test
    @DisplayName("Should throw UnknownHostException for empty address list")
    void testUnknownHostException() throws Exception {
        // Given: No addresses returned
        when(nameSvc.getAllByName(eq("unknown.host"), eq(true))).thenReturn(new Address[0]);

        // When/Then: Should throw UnknownHostException