IP Address – Determining Host Portion from a Given IP Address

ipip addressipv4subnet

I need to determine the subnetmask and Host Id of a given address: 175.142.213.217/22

This is what I have so far:

Address:    01010111.10001110.11010101.11011001
SubnetMask: 11111111.11111111.11111100.00000000 = 255.255.252.0

The part I'm stuck on is how to determine the Host Id.

Can someone please explain to me in great detail how I would get to that point from what I have so far (assuming my answers above are correct)

Best Answer

You have a subnet mask, but you need a host mask, which is just the NOT of the subnet mask (reverse the ones and zeros) to get 00000000.00000000.00000011.11111111.

AND the address and the host mask (only ones in both positions get to be one in the result) to get 00000000.00000000.00000001.11011001.

Convert that back to decimal (0.0.1.217) or give it as an offset into the subnet (473).

Related Solutions

Router – How Can a Router Change the IP Address

Your picture can't be viewed but if you have both networks directly connected to your router that networks are tipically used to explain Network Address Translation (NAT) Protocol. http://en.wikipedia.org/wiki/Network_address_translation

That is not NAT, is just a normal router connection. The goal of a router is interconnecting networks. The router you comment, for example, have this configuration:

Interface            IP
Serial0/0/0          10.2.2.1
FastEthe0/0          192.168.2.1

And it knows that each network is on that interfaces. But how can reach PC1 to PC0? Because there are static or dynamic routing: Router 1 have a sentence like that.

192.168.1.0 255.255.255.0 10.2.2.2

That means:

The whole network 192.168.1.0/24 can be reached with next hop 10.2.2.2 (The other side of your Serial Interface).

Routing Switch IP IPv4 IP-Address – Network Setup for Multiple Devices with the Same IP

Your drawing and idea have some problems:

Your router has multiple interfaces in the same network, but that will not work. Routers route between networks, not from a network back to the same network, so router interfaces must be in the different networks.
Switches are layer-2 devices, and they are ignorant of layer-3, e.g. IP. Layer-2 can carry any number of layer-3 protocols (IPv4, IPX, IPv6, AppleTalk, etc.) because they do not know or care about layer-3.

The idea of changing IP addresses on packets is NAT (Network Address Translation).

A real problem for you is that on whatever network a PC connected, changing the address on the PC to a different network address will stop the PC from communicating after you change the address.

Best Answer

Related Solutions

Router – How Can a Router Change the IP Address

Routing Switch IP IPv4 IP-Address – Network Setup for Multiple Devices with the Same IP

Related Topic