I'm trying to check if a symbol server is valid. According to this answer the server should serve /pingme.txt (this is also backed by the official docs here). However, the MS symbol server does not seem to adhere to this behavior (anymore?). The following query
curl -L -v http://msdl.microsoft.com/download/symbols/pingme.txt
gives me a 404. Some older, internal symbol servers we have in our company do actually have the /pingme.txt, also symbol servers backed by the local file-system seem to have it.
I've intercepted http requests done by Visual Studio and noticed they are sending User-Agent: Microsoft-Symbol-Server/10.1710.0.0. It doesn't seem to help. Note that accessing PDBs works as expected.
I'm looking for yes/no if the given URL is a symbol server.