KIS FRI UNIZA VPC and IP addressing  Each created VPC  Must have assigned an IPv4 CIDR block  Range of private IPv4 addresses  Required to be able communicate with each other or to outside  There is no possible to change the address range after the VPC is created  The largest IPv4 CIDR block size is /16.  The smallest IPv4 CIDR block size is /28.  IPv6 is also supported  with a different block size limit  VPC  Can be a single subnet (the same CIDR)  or several subnets (subsets of CIDR)  CIDR blocks of subnets cannot overlap 10 x.x.x.x/16 or 65,536 addresses (max) to x.x.x.x/28 or 16 addresses (min) VPC KIS FRI UNIZA Reserved IP addresses  Each subnet requires own CIDR block  For each CIDR five addresses are reserved  Network address  VPC local router (internal communications)  Domain Name System (DNS) resolution  Future use  Network broadcast address  VPC example:  IPv4 CIDR block of 10.0.0.0/16 is assigned  Provides 65,536 total IP addresses  Has four equal-sized subnets  Fire addresses reserved  => only 251 IP addresses are available for each subnet  Every instance in VPC gets a private IP address  Public must be requested 11 Subnet 1 (10.0.0.0/24) Subnet 4 (10.0.1.0/24) Subnet 2 (10.0.2.0/24) Subnet 3 (10.0.3.0/24) VPC: 10.0.0.0/16 251 IP addresses 251 IP addresses 251 IP addresses 251 IP addresses IP Addresses for CIDR block 10.0.0.0/24 Reserved for 10.0.0.0 Network address 10.0.0.1 Internal communication 10.0.0.2 Domain Name System (DNS) resolution 10.0.0.3 Future use 10.0.0.255 Network broadcast address 77