[Techtalk] LAN IP addresses changed after router reset

[Wei-Yee Chan]

Rudy Zijlstra wrote:
> No, any decent DHCP server will not do that, 
Well, it happened to me on several occasions, with a Netgear router and 
a Linksys router with a hacked firmware, so I know it can happen.

> as the RFC specifies that it should try to provide the same IP address 
> the the client each time. 
The routers obviously weren't trying hard enough then.

> For thisreason the DHCP server normally stores the IP addresses it has 
> handed out so
> it can know on reboot. 
>   
In fact, it has to record the IPs handed out.  However, that's IP 
leasing you're talking about, but whether the DHCP server is "smart" 
enough to always issue the same IP address to the same computer is quite 
another matter, isn't it?

> Many routers will not allow you to do this... This is most often found on
> full DHCP servers, but not in the simple implementations on embedded units. 
> Unless they be linux based and are using ISC dhcp  ;-)
I know that many do come with an IP-reservation-by-MAC-address function. 
My Netgear router for instance does that, and it cost me less than 
US$50. :-)  It runs on the standard firmware - not a hacked one.

If her router has limited DHCP functionality, then I suppose she could 
do away with that and simply hard-set the IP addresses, that is, set the 
IP addresses manually on each client computer.

Regards,

Wei-Yee Chan
http://chanweiyee.blogspot.com/