Using "nx.dnsp.co"

The domain "nx.dnsp.co" should always return NXDOMAIN. In addition, any subdomain such as "example.nx.dnsp.co" will also return NXDOMAIN. Theoretically, if your ISP is intercepting NXDOMAIN for the purpose of setting up advertising pages you can use this test to generate an advertising page with any keywords you wish.


Examples:

prompt>dig nx.dnsp.co ; <<>> DiG 9.10.2-P3 <<>> nx.dnsp.co ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 31925 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;nx.dnsp.co. IN A ;; Query time: 53 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Mon Aug 10 23:29:46 EDT 2015 ;; MSG SIZE rcvd: 39
Screenshot of Cox Communications abusing NX responses to serve advertising.