This is not the first time in my life when I have to convince a smaller corporation about using DNS service instead of /etc/hosts files and IP addresses. It might seem silly/funny at the first time, but imagine that there are many administrators who are lazy or just don't care and they deny to implement this service. Could we collect use cases and reasons why to do that?
Do you have any experience with such a situation? Please share!
Keep track of the time you spend updating /etc/hosts files, deploying the changes and keeping them in sync.
+1 for MikeyB's answer. As an extension, how would you convince a corporation that they need anything else? (How to justify the need for a new rack or switch, etc.?) Compare the alternatives, and provide a cost/benefit analysis for each option.
It really doesn't take that long to setup a reliable DNS solution.
Beyond the test necessary to update /etc/hosts files, how do you know if anything becomes out-of-sync? If you have everything pointing to a centralized set of servers, then you no longer have this concern. DNS can also easily be mirrored between servers and sites, so I would be very skeptical against any excuse that it makes things less reliable. (If the network goes down, your servers won't have much of a need for name resolution anyway. :-)
I would also point out that there can be relatively cheap ways of implementing this. Even if you don't set up your DNS yourself (or don't have the hardware or staff to implement it), that's quite easy to externalize.
If you're in a relatively small environment, nowadays, a number of fairly cheap domain name registrars let you edit a DNS configuration file related to your domain, via a relatively straightforward web interface. This can also work for local IP addresses, so you could have mymachinename.example.com as a A record to 10.0.0.1. Even if you don't want to pollute the official company domain name, you could get an alternative, more esoteric domain name with which to implement this. This type of hosting costs about $10/£10/€10 per year.
There are downsides with this approach, though (and it's not necessarily good practice):
For a larger network, of it the issues above matter, you should probably consider hosting your own DNS server.
I used to work for a company that had no internal DNS, DHCP or a consistent hardware process. Fun times. I feel your pain.
This situation is very similar to a programming language: you write a piece of code that does something and then you re-use the code. You do this because repeating the same task over and over is not cost effective. You also have the issue of updating all the instances of said code when a change is made, or a bug is found, etc. The same applies here.
Firstly, point out the central point of administration an internal DNS server would bring. An update in one place would bring joy around the entire network.
Secondly, make them aware of the bandwidth savings. Think about it, what DNS settings are being pushed out by DHCP? It would have to be some sort of external service. Having an internal server would eliminate the outbound round-trip which would speed things up for your internal users and decrease the bandwidth usage on your externally facing link. Win!
Security/control! You can black list known malicious DNS entries on your DNS server - i.e. you can have your DNS server resolve nasty-website-that-is-evil.tld to an internal page that explains why it's blocked (OK, this can be done with a proxy server as well, but there you go).
The list goes on and on, really.
I hope you've now got something to go by.
Kindof, I've seen this happen but not with 500 hosts!! that's unreal. More like 15 hosts.
If you're in charge of the IT dept then you can just say that this is what's going to happen. DHCP and DNS do not have big overheads, it can run virtual and is very easy to set up.
What OS is being run on those 500 machines? are they windows? how do you get along with windows file sharing? sounds like an ad-hok peer to peer network without a domain controller.
Adding a DC if it's windows will save you countless hours of messing around.
How much time do you spend administering the network with IP address conflicts and so forth? If it's sizeable then just adding DHCP/DNS is going to reduce this to almost nothing. So think of this as money saved.
It's much easier to administer 1 machine than 500. Make the change. And while you're at it, don't forget to have a secondary DC as a standby.
