It is as per design. You can use any of the networks mentioned in http://tools.ietf.org/html/rfc1918
3. Private Address Space The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets: 10.0.0.0 - 10.255.255.255 (10/8 prefix) 172.16.0.0 - 172.31.255.255 (172.16/12 prefix) 192.168.0.0 - 192.168.255.255 (192.168/16 prefix) Thank you, Chandan. -----Original Message----- From: motty cruz [mailto:motty.c...@gmail.com] Sent: Monday, January 20, 2014 9:55 AM To: users@cloudstack.apache.org Subject: Virtual Guest Cidr is not RFC1918 compliant advance networking CS4.2 Hello, when creating a new network using cloudmonkey i get the following error Virtual Guest CIDR is not RFC1918 Compliant any idea how to bypass this problem? Thanks,