what are the differences between automatic ip address and routable address?

Question

hi please help me to clear about the following matter

Answer 1

Well don't confuse two different items.
Automatic IP addresses are simply assigned by a DHCP server. They can be routable or non-routable addresses all depends on how and why the DHCP server was estabilshed.

Routable addresses are those which allow full internet access .. none routables are used for "private" networks. (Over simplification but for here that should do.)

Yahoo is located on a routable IP you can reach it.

If you are behind a local router -- it assigned you a local address like 192.168.1.1 or 10.0.0.1 etc. these are used within your local network and can't be directly reached by someone "outside" the local network. The router it self has a "wide area address" usually assigned by an ISP which is a routable address (or public address). The ISP may well automatically assign that also.

Answer 2

It is a little hard to answer this question properly without perhaps knowing a little bit about where it comes from. As has been mentioned, automatic IP Addresses are exactly that - ones assigned dynamically. Typically this is from a DHCP Server or through a PPPoE negotiation with your ISP. When the router you have at home assigns your workstation an address, it is really acting as a DHCP server and you are a client.

Routable address gets a bit more convoluted based on where it needs to be routable! On the Internet, a routable address is one that is not IANA reserved (like 192.168.0.0 or 10.0.0.0 are reserved as are MANY others). However, those reserved addresses are routable - just not on the public Internet. So another definition of a routable address is a NETWORK prefix - routnig table typically know nothing about hosts (like your PC) but rather only about networks where hosts reside.

I hope this helps some, and does not confuse the issue.

Answer 3

An automatic IP address is automatically assigned to your PC by the router/modem you are using, and changes when the PC connects to the network. Routable, or static IP addresses are assigned to a machine by the user. The main use for this is for P2P apps or application sharing, but may make network administration easier for the end-user.