Which ip blocks are reserved for private networks?

IPv4 private addresses:

• Class A addresses in the range 10.0.0.0 to 10.255.255.255
• Class B addresses in the range 172.16.0.0 to 172.31.255.255
• Class C addresses in the range 192.168.0.0 to 192.168.255.255

IPv6 private addresses:

• All IPv6 addresses with the prefix FC00::/7 are regarded as private.