getting ip address from mac address

Hi dear, can you explain to me in detail how to determine ip address from mac address?
Thanks
Chibuzo

@echo off
:Start
IF "%4"=="" GOTO Help
SET thirdOctet=%1
SET thirdlimit=%2
SET fourthOctet=%3
SET fourthlimit=%4
IF "%5"=="" SET net1=131
SET net1=%5
IF "%6"=="" SET net2=162
SET net2=%6
IF "%7"=="" SET timeOut=100
SET timeOut=%7
GOTO IP

:IP
IF %fourthOctet% GEQ %fourthlimit% GOTO PART2
SET ipadd=%net1%.%net2%.%thirdoctet%.%fourthOctet%
ECHO Processing %ipadd%
GOTO PART1

:PART1
ping -n 1 %ipadd% -w %timeOut% > junk.del
GOTO Update

:Update
SET /A fourthOctet=%fourthOctet%+1
GOTO IP

:PART2
IF %thirdOctet% GEQ %thirdlimit% GOTO END
SET fourthOctet=1
SET /A thirdOctet=%thirdOctet%+1
SET ipadd=%net1%.%net2%.%thirdOctet%.%fourthOctet%
ECHO Processing %ipadd%
GOTO PART1

:Help
ECHO Usage :
ECHO C_ARP 3rd_octet 3rd_limit 4th_octet 4th_limit [Optional 1st_octet] [Optional 2nd_octet] [Optional Timeout]
----------------
ECHO Example Usage 1 :
ECHO C_ARP 145 147 1 255
ECHO will scan the ip ranges from 131.162.145.1 to 131.162.145.255
ECHO and 131.162.146.1 to 131.162.146.255
ECHO and 131.162.147.1 to 131.162.147.255
ECHO C_ARP 145 147 1 255 156 230 10
ECHO will do the same thing except that 131 will be replaced by 156
ECHO and 162 will be replaced by 230
ECHO the timeout will be 10 instead of 100
ECHO NOTE :
ECHO The parameters 1st_octet, 2nd_octet and Timeout should be
ECHO entered in sequence if you use it.
ECHO .....................................................................
ECHO ABOUT THE BATCH FILE
ECHO .....................................................................
ECHO I created this as i needed a way to get the ip address
ECHO from the mac address, since the hostname changes
ECHO depending from where you are logged in (ex, Carnegie or Library)
ECHO This batch script pings all the ip addresses of the range of
ECHO 131.162.third_octet.fourth_octet to 131.162.third_limit.fourth_limit
ECHO This in effect fills the cache tables of your ARP, which you can
ECHO then use to determine the ip address from the mac address you have!!
ECHO Use arp -a to display your arp table and Use arp -d * to clear your arp cache
---------------
ECHO DEVELOPED BY KHALSA
ECHO CONTACT : 050188s@acadiau.ca
ECHO When one door closes, another opens
GOTO LETGO

:END
del junk.del
arp -a > results.arp
ECHO ARP table saved in file results.arp, Good luck !!
:LETGO

[ot]

lol ... ctlaltdel ... you shred!!!!

[/ot]

I think this sequence:
SET fourthlimit=%4
IF "%5"=="" SET net1=131
SET net1=%5
IF "%6"=="" SET net2=162
SET net2=%6
IF "%7"=="" SET timeOut=100
SET timeOut=%7

needs to be:
SET fourthlimit=%4
SET net1=%5
IF "%5"=="" SET net1=131
SET net2=%6
IF "%6"=="" SET net2=162
SET timeOut=%7
IF "%7"=="" SET timeOut=100

to work.