Private IP address ranges and the APIPA

Certain IP address ranges have been reserved for private network use.  These are listed in RFC 1918 http://tools.ietf.org/html/rfc1918.  These ranges can safely be used for internal networks.

Microsoft has also allocated a block of addresses called the Automatic Private IP Addressing (APIPA)  These are used by machines when no IP has been allocated and DHCP is not available. These auto allocted IPs are tomporary and will be superced as soon as a DHCP address becomes available.  http://support.microsoft.com/kb/220874

IP Range Start	IP Range End	Number of hosts	CIDR	Subnet	Name
10.0.0.0	10.255.255.255	16 777 216	10.0.0.0/8	255.0.0.0	24-bit block
172.16.0.0	172.31.0.0	1 048 576	172.16.0.0/12	255.240.0.0	20-bit block
192.168.0.0	192.168.255.255	65 536	192.168.0.0/16	255.255.0.0	16-bit block
169.254.0.0	169.254.255.255	65 536	169.254.0.0/16	255.255.0.0	APIPA

When building lab or setting up new environments use the table as a guide to pick Which black or IPs or even part of the block that you want to use.  Bearing in mind that the some of address may already be route-able in your private network.