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RUM - frontend application not visible


Dear Gurus,

I have an issue with IIS on Windows that is not showing neither in Default App or Specifically created Frontend App,

We have successfully enabled all capture setting required as we did in other Apps but is not capturing anything

However, if we invoke the application URL  by IP it shows in the default application, otherwise it is not showing anywhere.

The two IIS services are serving the website via a load balancer and the frontend app that we created in DT checks for the rule of the domain that the users are using, They do not use the DNS ip to invoke the URL. 

Any idea, what is going on, any config you suggest in Dynatrace to resolve this issue

I appreciate your support in this,



DynaMight Legend
DynaMight Legend

There are practically unlimited reasons for this. I'd suggest using dtHealthCheck as the user agent and then checking the response headers. You can see that in action in one of the community episodes here

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner


In addition to @Julius_Loman advice, you need also to make sure of all the security requirements for RUM in case that you are using loadbalancer and most probably a WAF.




Dynatrace Certified Professional - Dynatrace Partner -

Yes exactly. First, check if the JavaScript gets injected. If not, validate it using the dtHealthCheck or you can also use the Health Check in the UI:


Maybe the RUM JS cannot be downloaded, or the beacon it sends back cannot be received because of a different context path. 

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner


We ran the health check. The two items are not clear. As I said the APP the URL with IP is showing correctly in the defaults APP but not showing in the dedicated APP that I created. It means the injection is working but somehow the DT injection is not working on the domain (see attached screenshot)1.PNG

Most likely the domain is not propagated to the webserver (host request header is different on the IIS host as some reverse proxy modifies it). Dynatrace then cannot determine the host name. Check the host header on the webserver in Dynatrace (in the distributed traces).

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner


Maybe because you are using opt-mode? It is disabled by default.

If it is turned on, be sure you are calling "dtrum.enable()".

This tip maybe helps.

Best regards

❤️ Emacs ❤️ Vim ❤️ Bash ❤️ Perl


resolved now by enabling opt-mode.

Nice, maybe you want to say disabling opt-mode, right?

❤️ Emacs ❤️ Vim ❤️ Bash ❤️ Perl


indeed. resolved now by disabling opt-mode. The description of this flag is confusing may be a rephrase of the description needs to be updated.


@MarwanC Thanks for this post, I had similar issue which got fixed after disabling opt-mode. Even i was bit confused after the going through the description. However, it got fixed.



Dynatrace Professional Certified

To put it bluntly, the current description is like this. 

"With Data-collection and opt-in mode enabled, Real User Monitoring data isn't captured until dtrum.enable()
is called for specific user sessions"

As this is the most important flag to make the whole capturing to work,

I suggest Dynatrace product team to rephrase it to the layman to avoid extra double work

I suggest the following:


If the Data-collection and opt-in mode (radio button off) are disabled, Real User Monitoring data
will be captured without needing to call dtrum.enable() for specific user sessions.
When the Data-collection and opt-in mode are enabled (radio button on), Real User Monitoring
data won't be captured until dtrum.enable() is called for specific user sessions.

I hope this is clear to everyone

I have seen many occasions where the double negation is used I will try to help from experience
when possible.


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