4 ms·

For those wondering why: It's a commonly forgotten edge case, websites forget to normalize the hostname, the content is still served, but there's no hostname m

• gorkish 6y ago
  I would disagree that this is an "edge case;" it's a rather fundamental feature of DNS that is relied on every time a record from one domain references a record in another domain. The dot at the end fully qualifies the name and makes it unambiguous. Without the dot, unqulified DNS names are treated as members of their parent SOA. This is why when creating CNAME or NS or MX records that reference a foreign domain, you have to specify a dot at the end, and when you don't they dont resolve as expected. So a machine with a search domain of 'foo.com' looking up 'www.google.com' should ideally seek the record for 'www.google.com.foo.com' first. Conversely, looking up 'www.google.com.' is more specific and returns google's ip even if 'www.google.com.foo.com' were to exist. The reason it's not common is because all DNS client behaviors have been modified for convenience to avoid this; in basically every resolver any query containing at least one dot is automatically treated as if it were a fully qualified name. So behind the scenes, the DNS resolver is caring very much about the trailing dot and adding it to nearly every query; it's just typically hidden from users.
  • robbrown451 6y ago
    It's an edge case from the point of view of the people who develop the ad serving software. If 99.9 percent of urls don't have that dot at the end, then it's an edge case.
• inetknght 6y ago
  It's not only a commonly forgotten case (I disagree about it being an edge case), but the Anaconda installer used by Fedora removed the ability to enter a FQDN for the hostname during system setup. [0] https://bugzilla.redhat.com/show_bug.cgi?id=1648107 https://bugzilla.redhat.com/show_bug.cgi?id=1648107
• tyrust 6y ago
  Or they could read the OP from which you copied.