unknown node or service
I don't know why the program can not connect to `xmr.coinfoundry.org:3032`. Please see below

```
    "pools": [
        {
            "url": "xmr.coinfoundry.org:3032",
            "user": "49sdbG2dKnY...........................9Fvee6BKqV...............pKvdDj5uL5xJn",
            "pass": "x",
            "rig-id": null,
            "nicehash": false,
            "keepalive": true,
            "variant": 1
        }
    ],
```
The output is
```
$ ping coinfoundry.org
PING coinfoundry.org (138.201.154.172) 56(84) bytes of data.
64 bytes from static.172.154.201.138.clients.your-server.de (138.201.154.172): icmp_seq=1 ttl=43 time=134 ms
^C
--- coinfoundry.org ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 134.018/134.018/134.018/0.000 ms
$ ./xmrig-nvidia 
 * VERSIONS     XMRig/2.7.0-beta libuv/1.9.1 CUDA/9.20 gcc/7.2.0
 * CPU          AMD Ryzen 7 1800X Eight-Core Processor          x64 AES
 * GPU #0       PCI:0000:26:00 Quadro M2000 @ 1162/3303 MHz 56x18 0x0 arch:52 SMX:6
 * ALGO         cryptonight, donate=5%
 * POOL #1      xmr.coinfoundry.org:3032 variant 1
 * COMMANDS     hashrate, health, pause, resume
[2018-10-17 19:52:51] [xmr.coinfoundry.org:3032] DNS error: "unknown node or service"
[2018-10-17 19:52:56] [xmr.coinfoundry.org:3032] DNS error: "unknown node or service"
[2018-10-17 19:53:01] [xmr.coinfoundry.org:3032] DNS error: "unknown node or service"
[2018-10-17 19:53:06] [xmr.coinfoundry.org:3032] DNS error: "unknown node or service"
```
What is the issue?