Here is the request header:
GET /proxy/proxy.ashx?https://demographics7.arcgis.com/arcgis/rest/services/USA_Demographics_and_Boundaries_2017/MapServer... HTTP/1.1
Host: myproxyserver.com
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36
Accept: */*
Referer: https://localhost/my_application
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.8
Cookie: [removed]
And here is the response header:
HTTP/1.1 200 OK
Cache-Control: max-age=0,must-revalidate
Content-Type: text/plain;charset=utf-8
ETag: 6dfb1ba3
Vary: Origin
Server: Microsoft-IIS/8.5
Set-Cookie: AGS_ROLES="nGGHe9fnJdtqgrxv/F457aPODB3PII6+MSSUUbBUPUTFqmHBA0KbNNNKphQAiCnKG1HjLTBjpl0/sBdgKzNqdPYLY75CroUOHRS1I8+SG87wUFamgBZb7OKBemucaf3O/3MbDnjgy1VS02jMPpD3O9QK2LrPN/lN8P5gvUvHjB8FY19FcRB9SKLYwGievzdwfKT9kJyRGaUPfWHpL1SMJ+n9Pn+xGBREr+oTFHXazQBaD59XcKRqRpTvrB5bnIWcmGy6+jpfv11KySMB1lEO6I6ZOPEy8yCxyQJvB6Ebot8="; Version=1; Max-Age=60; Expires=Mon, 16-Oct-2017 16:21:41 GMT; Path=/arcgis/rest; HttpOnly
Server:
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Access-Control-Allow-Origin: *
Date: Mon, 16 Oct 2017 16:20:39 GMT
Content-Length: 239728
And here is a link to the body of the request - it's huge! https://pastebin.com/Zq0LAm8i
I'm only specifying these layers, so I'm not sure why it's making such a huge request:
outFields: ["NAME", "EMP_CY", "INDMANU_CY", "MEDHINC_CY", "OCCTRAN_CY", "POPDENS_CY", "POPGRWCYFY", "TOTHH_CY", "UNEMP_CY", "CIVLBFR_CY", "UNEMPRT_CY"]