The exchange service that comes with NAV 2017 does not work. It is with Yahoo, and Yahoo has stopped allow its use. So if you want to import currency exchange rates automatically, you need to setup a service.
I have done this for several businesses and used www.floatrates.com as it is reliable and free. There are other services which require a paid subscription.
To get started, go to the Currency Exchange Rate Services page, and click New to create a new record for a service. Enter a code and description: I used FLOATRATE and Floating rate. On the Service fasttab, Service URL field, enter http://www.floatrates.com/daily/aud.xml for the Australian dollar feed service in xml format.
On the Field Mapping fasttab, enter the values exactly as I have done in the below screenshot.
Tick the Enable box on the General fasttab, then click OK. You will be prompted for creating a Job Queue Entry. Create the Job Queue Entry, and set it up for daily. As the exchange rates are only updated every 12 hours, there is no reason to run the job multiple times a day.
After your job runs, check the Currencies page. If your rates are not updated, or perhaps only one rate is updated, and you have double checked all the settings, you may want to try editing codeunit 1203. I found that when the xml file was being read, the codeunit assigned the same line no. to all records, and consequently processed only one exchange rate.
I made a change to function ParseParentChildLine as below:
Now try running the Currency Exchange Service again. The rates should all be updated.