TraceBack - 10.10.10.181
TraceBack is a linux machine created by Xh4H. This has more excepted hidden thing which made this into a very easy and simple one to exploit and the privileges escalated. Unlike other active box this is Beginner friendly and Noob can also walkthrough this one.
Adminer - 10.10.10.187
Admirer is a linux machine crafted by polarbearer & GibParadox . Its a box which is kept for pratice of real time scenario for pentest pratice with realtime attacks and exploits with metasploit modules available with out dated version of CMS service in webhosting.
OpenKeyS - 10.10.10.199
OpenKeyS is a OpenBSD machine crafted by polarbearer & GibParadox. This machine is medium level rated machine and by seing the matrix rating we can find out, the machine is for predefined vulnerability which was disclosed this year for OpenBSD's Skey exploit.
Doctor - 10.10.10.209
Doctor is a linux machine in easy category and design by egotisticalSW. By seing the rate matrix, the machine is meant for ctf and available exploit practise and this machine is under easy category. So I guessed this was a beginner friendly machine.