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To make sure you can communicate with your Swarm cluster, open a command prompt window and ping a node in the cluster:

ping cluster-node-ip 

For example:

ping 172.16.0.32 

If the node does not respond, try to ping another node IP address. Do not continue until you can successfully ping a node in your cluster.  This verifies ICMP reachability but not necessarily that the node is available on port 80 for HTTP requests.  It is not definitive, as a node could potentially be unavailable via ICMP through the network, but still be available via port 80.  Regardless, it is a good, simple test for reachability.  Similarly, you could run the following to test port 80:

telnet 172.16.0.32 80

How to Correctly Use cURL

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HTTP/1.1 401 Unauthorized
WWW-Authenticate: Digest realm="CAStor administrator",
nonce="e9d618c06bbeca15e7568aca2f
opaque="f9bcffd26d1bede5419a2b30cbcff976",
stale=false, qop="auth", algorithm=MD5
WWW-Authenticate: Basic realm="CAStor administrator"
Content-Length: 51
Content-Type: text/html
Date: Fri, 04 Nov 2011 16:22:53 GMT
Server: CAStor Cluster/6.0.0
Allow: HEAD, GET, PUT, POST, COPY, APPEND, DELETE
HTTP/1.1 201 Created
Content-UUID: 68aeb6c78e4ca0101f3936c03fa26e72
Location: http://172.16.0.35:80/?domain=mycluster.example.com      com
Volume: 064d2cc2392810dcc2d04f7b1023ecc7

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