Quote data not matching my data feeds askexchange 15?

When I try to fetch a quote I get data which completly differs from my sources and datafeeds. This is a response example I get.

“status”: “success”,
“symbol”: “NVDA”,
“last”: {
“askprice”: 592,
“asksize”: 1,
“askexchange”: 15,
“bidprice”: 490,
“bidsize”: 1,
“bidexchange”: 15,
“timestamp”: 1615323599910414800

Where askexchange is 15. What is this 15 related to? I couldnt find any table holding numbers. I am subscribed to pro plan with 2 alpaca accounts and both of them return these wrong market data values.

Please clarify