Browsers lookup host ip addresses by various means. The original name is then delivered to the remote computer which, if run as a wiki farm, will serve content from the site so named.
Notice that host names and host ip address are allocated by different organizations for different purposes. The network infrastructure providers allocate ip addresses based on geographic area and the efficient transmission of data. The separation allows named service to be moved freely by updating lookup tables.
Browsers typically consult a service of the client operating system to perform the name lookup. Thus the particular browser and the particular client os play a key role in deciding how sites will be named within a remote wiki farm.
# Host File
One computer can know of others by entering name and address into a locally held file, often /etc/hosts.
The host file on my laptop includes entries for localhost and several other computers on my lan.
127.0.0.1 localhost 10.0.3.201 wikiduino 10.0.1.31 pi
Host files date back to when ten computers was considered a large network. With hundreds or thousands it becomes impossible to keep host files up to date.
# Zeroconf
Computers on a LAN can figure out for themselves how each is named and numbered. The protocol they use goes by different brand names including Rendezvous, Bonjour, Avahi and many protocol specific acronyms. All variations provide network access to other computers and network devices like printers with zero configuration by their users. wikipedia 
On apple computers one enters a name for their computer on the System Preferences ⇒ Sharing dialog. When I enter the name 'nr' for my laptop, the dialog advices me how other zeroconf computers on my LAN will address me.
Computers on your local network can access your computer at: nr.local
# DNS
The highly configurable Domain Name Service (DNS) provides the familiar dot-com style names made famous by the web. Network administrators the world over setup programs like 'named' and 'bind' to feed information into this distributed system. See Domain Names
Authority to assign names are delegated progressively from organizations managing top-level domains (TLD) like .com, .edu, .us, .uk and so on, to registrars of second level names and from their to the owners of these names to subdivide further as they see fit.
Name registrars and platform as a service providers (paas) will have developed web applications for managing the assignment of ip addresses to domain names. Regretfully, these tools are no longer user-friendly since they hide the desired operations behind relentless up-sells and misleading marketing fud.