Yes, you are right, all international shipments of TCS are being handed over to DHL in Dubai and from their onwards, DHL delivers it as per their tracking number, of course you can also search the tracking on DHL website even if you dont have DHL no. by searching through shipper reference no. in shipper reference, you can enter tcs number and select dates accordingly and there, you will find the result. or,
The tracking no of DHL can also be found on tcs tracking page, its Agent reference no. or sort of like that in the search result page at the top.