Update faq.md

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@@ -397,3 +397,6 @@ I guess my question is more specifically: “Will the compliance checker look at
 
 *Question*: The result of my POST contains the following failed message in its ExchangeInfo: "java.lang.IllegalArgumentException: KB gave outgoing binding Binding [...], but this doesn't have a matching incoming binding!". What does this mean?
 - *Answer*: The reason this error is given, is the following: REACT KIs that contain both an argument and result graph pattern and these two graph patterns share a variable name, the knowledge engine expects all values for this variable in the result binding set to also occur as a value of the variable in the argument binding set. This has to do with how these graph patterns are internally used to form if … then … rules. If this is not the case, it gives the above failedMessage. If this shared variable in the argument and result graph patterns is intended to be the same, make sure you align the values of this variable in the result binding set with the values of this variable in the argument binding set. If the variable is not intended to be the same thing, you can rename one of them to prevent the knowledge engine to expect them to share values.
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+*Question*: <a name="setup_keruntime"></a> There is an existing Knowledge Network with a Knowledge Directory (KD) and multiple Knowledge Engine Runtimes (KERs). How do I setup my own KER and configure it such that it participates in the existing Knowledge Network?
+- *Answer*: Every Knowledge Engine Runtime (KER) in distributed mode consists of two APIs: [Knowledge Engine Developer REST API](https://github.com/TNO/knowledge-engine/blob/1.2.5/smart-connector-rest-server/src/main/resources/openapi-sc.yaml) and the [Inter-Knowledge Engine Runtime API](https://github.com/TNO/knowledge-engine/blob/1.2.5/smart-connector/src/main/resources/openapi-inter-ker.yaml). The former is started on port `8280` by default and you use this API to register your Knowledge Base and Knowledge Interactions. The latter API is meant for internal communication between KERs and you do not need to use it yourself. However, you do need to make sure this API is reachable for other KERs in the Knowledge Network. By default this API is available on port 8081, but sometimes you need to change this port using the `KE_RUNTIME_PORT` environment variable. Make sure the latter API of your KER is accessible from the internet and configure its URL when starting the KER with the `KE_RUNTIME_EXPOSED_URL` environment variable. To set this up correctly, you typically install a reverse proxy like NGNIX and open the correct ports in the firewall of the server. For this you need to contact the administrator of the server you are using. A KER starts in distributed mode when it detects the `KD_URL` environment variable. This variable points to the Knowledge Directory of the Knowledge Network. You can configure it using environment variables `KD_URL=<knowledge-direcotry-url>`. If the Knowledge Directory is protected using Basic Authentication, you can add the credentials to the KD_URL as described [here](https://stackoverflow.com/a/50528734).