Administration experience:
Microsoft Windows (version from 3.10 to windows 10)
Microsoft Windows Server (version from Windows NT to Windows 2012)
FreeBSD (version from 2.1.7 to 11+)
Linux (since 1998 until today)
Solaris (version from 5.9 to 5.10, since 2005 to 2007)
Services:
DNS, DHCP, Web (apache, nginx, iis), POP3, SMTP, IMAP, Web-mail services (on various software solutions), VoIP (Asterisk), TCP/IP (routing: RIP, OSPF, BGP), virtual ethernet network technology and other second and third level model OSI (Cisco, 3com, Allied-Telesis)