Dynamic DNS

[bind at col7.metta.lk]

Hi all,

I am running a small setup where I have 2 boxes on a 128K lease line 
and one box on an ADSL dynamic ip line

My domain is http://metta.lk
and the name of the 3 boxes is

Lease line
	dhamma.metta.lk	RH 6.2, bind 8.3.3-REL (tarball) 
	mail.metta.lk	RH 8.0

ADSL
	books.metta.lk	Mandrake 9.2 bind (latest tarball)

I have 1 zone file for metta.lk with all the details in it.
I now have to set up this domain to provide for the dynamic IP for 
books.metta.lk , to make books.metta.lk accessible to the world.
I will be upgrading my bind 8.3.3-REL to the latest version of 9.x

My question is:
Can I have all 3 in the same zone file ?
What is the ttl that I should give for the ADSL books.metta.lk ?

I am planing to use the setup of /chroot/named
Where should the Tsig key be placed ?

Thank you in advance
Mettavihari

-- 
A saying of the Buddha from http://metta.lk/ 
If from anybody one should understand the Doctrine preached by the Fully Enlightened One, a devoutly should one revere him, as a Brahmana reveres the sacrificial fire. 
Random Dhammapada Verse 392