[stardek]

Can anyone explain what happens when I click this?

I'm on the University of Waterloo network and I get sent to [1], rather than what I get when I add the period for: http://ai./

[1] https://uwaterloo.ca/artificial-intelligence-group/

[the_pwner224]

Here's my /etc/resolv.conf (I'm running Linux, though the theory is cross-platform):

# Generated by NetworkManager

search my-university.edu

nameserver their-dns-server-ip

nameserver their-other-dns-server-ip

nameserver their-third-dns-server-ip

DNS queries get sent to the nameserver, but the search domain is what's important here. The search domain is used to resolve non-fully-qualified domain names. So if I just type in http://cs, that's not a FQDN since there are no .s - with cs.my-university.edu, it goes edu->my-university->cs, but just cs is not fully qualified. So since the search domain is 'my-unversity.edu', if I just type in http://cs into the browser, it will look up cs.my-university.edu.

In your case, going to the URL ai.uwaterloo.ca redirects to the URL you linked. Adding the trailing . to ai makes it fully qualified, so going to "http://ai." makes your DNS lookup just 'ai' instead of 'ai.uwaterloo.ca'.

The search domain stuff is mostly useful for addressing other devices on the network. My home router sets the search domain to 'lan' when configuring DHCP devices, so I can use my-server as a hostname and it will resolve to my home server's IP. E.g. "ssh my-server" will turn into "ssh my-server.lan" which gets resolved by the router's DNS server to the correct IP.

[JdeBP]

I expect that several people can.

* http://jdebp.uk./FGA/web-fully-qualified-domain-name.html

    % dnsqr a ai.uwaterloo.ca.
    1 ai.uwaterloo.ca:
    74 bytes, 1+2+0+0 records, response, noerror
    query: 1 ai.uwaterloo.ca
    answer: ai.uwaterloo.ca 286 CNAME wms-redir1.uwaterloo.ca
    answer: wms-redir1.uwaterloo.ca 286 A 129.97.128.216
    %
    % fetch -v -o /dev/null http://ai.uwaterloo.ca./ 2>&1|head -n 6
    looking up ai.uwaterloo.ca.
    connecting to ai.uwaterloo.ca.:80
    requesting http://ai.uwaterloo.ca./
    301 redirect to https://uwaterloo.ca/artificial-intelligence-group/
    looking up uwaterloo.ca
    connecting to uwaterloo.ca:443
    %