Kazohi Blog

  Seven Second Subnetting Convert IP address and subnet mask to decimal Use chart to convert between CIDR-block notation and decimal Same chart also shows the number of devices per subnet Determine network/subnet address Second chart shows the starting subnet boundary  Determine broadcast address Chart below shows the ending subnet boundary  Calculate first and last usable IP address Add one from network address, subtract one from broadcast address

VLSM (Variable length Subnet Masks) Class-based networks are inefficient The subnet mask is based on the network class Allow network administrators to define their own masks Customize the subnet mask to specific network requirements Use different subnet masks in the same classful network 10.0.0.0/8 is the class A network - 10.0.1.0/24 and 10.0.8.0/26 would be VLSM Number of subnets = 2 subnet bits Hosts per subnet = 2 host bits - 2

Assigning IPv6 Address Internet Assigned Numbers Authority (IANA) provides address blocks to RIRs (Regional Internet Registries) RIRs assigns smaller subnet blocks to ISPs (Internet Service Providers) ISP assigns a /48 subnet to the customer

Classful Subnetting Very specific subnetting architecture Not used since 1993 But still referenced in casual conversation Used as a starting point when subnetting Standard values The construction of a subnet Network address The first IP address of a subnet -Set all host bits to 0 (0 decimal) First usable host address One number higher than the network address Network broadcast address The last IP address of a subnet - Set all host bits to 1 (255 decimal) Last usable host address One number lower than the broadcast address

Networking with IPv4 IP Address, e.g., 192.168.1.165 Every device needs a unique IP address Subnet mask, e.g., 255.255.255.0 Used by the local device to determine what subnet it's on The subnet mask isn't (usually) transmitted across the network You'll ask for the subnet mask all the time What's the subnet mask of this network? Default gateway, e.g., 192.168.1.1 The router that allows you to communicate outside of your local subnet The default gateway must be an IP address on the local subnet Special IPv4 addresses Loopback address An address to yourself Ranges from 127.0.0.1 through 127.255.255.254 An easy way to self-reference (ping 127.0.0.1) Reserved addresses Set aside for future use or testing 240.0.0.1 through 254.255.255.254 Virtual IP addresses (VIP) Not associated with a physical network adapter Virtual machine, internal router address