Does a wifi router have to handle DHCP for its clients?

Question

I'd like to manage the IP addresses within my network a little better than my router currently allows.

Before I embark on a journey of learning and (self) discovery, I would first like to know if what I am wanting to do is in fact possible before I waste the next few hours/days on it.

Does a WiFi router have to handle DHCP requests for (any of, but specifically) the WiFi clients?

I want to set up a R&D network within my home mainly for the purpose of developing and testing websites internally on my network. I want to have FQDNs (such that http://test.loc or http://test.bob) resolve for any computer and device on my home network.

I know that I can change the hosts files to allow a computer to connect, but I want to be able to test mobiles and tablets as well. My router does support unqualified names such that http://server1, http://server1/page_url and http://server2/other_page resolve, but it doesn't support http://server1.loc/example or http://server2.internal/example.

I'm asking because although I know I can set up the wired network like this, with the DHCP server handing out the IP addresses that I want any specific machine to have (and I want everything specifically designated), and DNS to resolve those internal addresses and forward externally (to my ISPs DNS) those that aren't; but I'm not sure of the mechanism involving those connecting via WiFi.

Since the WiFi/modem/router is handling WiFi generally, does that connection mechanism require that IT designates the IP address to the device or can/would it ask/look for a DHCP server and assign as handed out by the server I setup?

Note: I do have a good(-ish) router, and I mostly like it, it just doesn't support specifically what I'm after. I can get into this if you want, but that's not the question here, this (and what's above) is more just a little background as to why I want to do this. My router is presently the central "everything" and I want to split some of it's functionality to a custom server that I have more control over (DHCP & DNS are the specific two, but maybe more down the track). If anyone is interested, I am currently using a Fritz!box 7390

Answer 1

Short answer: No, a wifi AP does not have to take care of DHCP and DNS too. Furthermore, they have to support disabling those services, as often you can have more than one in one location/network.

For instance in an enterprise or University, there are DHCP and DNS servers for all the network, and it is not the wifi router(s) doing that.

You can much pretty well use Linux servers for that.

Long answer:

The DHCP mechanisms in wifi are pretty much the ones in a cabled network once the layer 2 is authenticated.

You can either maintain the DHCP on the wifi side, and configure the DHCP to give as DNS your server, or disable DHCP altogether and put your server doing the DHCP; as long as the wifi device is in the same netblock/broadcast domain of the DHCP server. If that is not the case, dhcp relaying has to be involved, which complicates the setup and is only justified in an enterprise environment. Or having diferent DHCP servers per netblock/broadcast domain.

If using an alternated DHCP/DNS server I strongly recommend for it to be connected via cable for better stability of service.

As for machines, if you have requirements for them to have specific IPs and names, you can pin the MAC address of them to specific IPs in the DHCP server.

I also recommend creating a local domain in DNS. Whilst you do need anything as powerful as BIND, I do recommend using it over the alternatives, again because you will need it in bigger projects, and because it has very interesting anti-DoS and blacklisting functionalities.

You have to create a domain for DNS. For instance, domain.home. Avoid .local as it is associated with zeroconf services.

The Fritz!Box is a very interesting piece of equipment, and it is widely used in Germany. It can do all of this, however for better control and learning more, I recommend offloading some of it´s functions to the Linux server.

I also have at home a Debian server/router in the place of your FritzBox. It works as my firewall, IPsec VPN, DNS, DHCP and works as my phone/voIP PBX with asterisk.

The TP-Link with openWRT (Linux), only does wifi and does not do routing; so all the remaining services are done in the same network by my Linux server.

As for the specific software for Linux, you have ISC DHCPD for DHCP, ISC BIND for DNS, asterisk for the PBX, and strongWAN or openVPN for VPN.

I also have no idea if you are buying new machines; a very interesting one for toying around with network concepts at low cost is the Lamobo R1. ARM technology, an internal switch port with 5 gigabit ethernet ports supporting VLANs, a wifi chip (that sucks), and a SATA interface.