Let's create a binary TCP imposter with multiple stubs:

POST /imposters HTTP/1.1
Host: localhost:<%= port %>
Accept: application/json
Content-Type: application/json

{
  "port": 4547,
  "protocol": "tcp",
  "mode": "binary",
  "stubs": [
    {
      "responses": [{ "is": { "data": "Zmlyc3QgcmVzcG9uc2U=" } }],
      "predicates": [{ "contains": { "data": "AgM=" } }]
    },
    {
      "responses": [{ "is": { "data": "c2Vjb25kIHJlc3BvbnNl" } }],
      "predicates": [{ "contains": { "data": "Bwg=" } }]
    },
    {
      "responses": [{ "is": { "data": "dGhpcmQgcmVzcG9uc2U=" } }],
      "predicates": [{ "contains": { "data": "Bwg=" } }]
    }
  ]
}

We're sending a base64-encoded version of four bytes: 0x1, 0x2, 0x3, and 0x4. Our first predicate is a base64 encoded version of 0x2 and 0x3. The response is a base64-encoded version of the string "first response":

echo 'AQIDBA==' | base64 --decode | nc localhost 4547

first response

Next we'll send 0x5, 0x6, 0x7, and 0x8, matching on a predicate encoding 0x7 and 0x8:

echo 'BQYHCA==' | base64 --decode | nc localhost 4547

second response

The third stub will never run, since it matches the same requests as the second stub. mountebank always chooses the first stub that matches based on the order you add them to the stubs array when creating the imposter.