Joe & Sesil Morris (NTM) wrote:
Clint Tinsley wrote:
The D in DHCP is for Dynamic which is not Static. Two approaches what could be considered "static" IP addresses...
The dynamic part is not dynamic address selection, but dynamic configuration. It's purpose is to configure every machine on the network from one source instead of configuring each machine.
Well, sort of. Yes, it does push out to each machine the network configuration information of gateway, netmask and DNS which is all pretty "static" to the "connection" so that you don't have to manually configure this information. However, the real purpose of dynamic is to provide IP address assignment (as opposed to selection) from within a pool of available IP addresses which is where lease times comes into play. If lease times are short and according to what I have learned over the years is that at 50% of the lease time and if you had not "renewed" your lease, that IP address is released for assignment to another host. If you want the "Dynamic" IP address to be "permanent" subject to possible changes resulting from the DHCP table being flushed or changes in network card mac addresses, you "max" out the lease time in the router.
I do know some providers are misusing DHCP to intentionally change IPs to keep people from web hosting on their net.
On Dial-up's, the IP is actually static and assigned to a particular modem (I worked with a regional ISP for a time). On fixed connections, the point is correct that the ISP's do change the IP addresses to prevent users from setting up webservers, etc, unless you pay for such services. I believe the originator of this thread was requesting information on DHCP being provided by a router as opposed to a DHCP service being provided by a Linux box and it was in the router context that I provided this answer.