If you only need it for a month and aren't going to be sending too much traffic to it, you can get free domain names for a few ccTLDs (.tk, .ml, .cf, and .ga) at
freenom.com. I've heard of some people having issues with them being taken over by the company for advertising after receiving enough traffic, and you aren't technically the owner for free domain names (the company is, but you have control over it; different for paid ones). However, I've never had any issues with it for about a year save for one caused by client-side validation and a bit of hacking on my part, so you should be fine.
Except now that I check, I've apparently lost the domain sometime in the last three days. That'll be a pain to fix. YMMV, I guess.