Internal DDNS, ARP....questions.

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Karandras

[H]ard|Gawd
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Feb 16, 2001
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Hey all. Still all about learning Linux and I've got a CentOS4 box up with BIND for a caching DNS server, the DHCP service is handled by a Cisco 871. My Boss says that we can do internal DDNS and update the DNS A records via the server or computer's MAC address (uses arp?). I've never seen this process and if there is such a thing I can't find documentation on how to set it up or how it will work.

Can anyone point out some documentation or inform me how it works?:confused:

Thanks!
 
Alright that was quick. Guess my searching skillz aren't as 1337 as they used to be ;-)

Do you know how this process works? Does the DNS server request the IP from the DHCP server via a MAC address? So the DHCP server searches it's arp tables for that mac and hands out the corrosponding IP?

If that is the way it works how do I setup BIND name.conf to look at the DHCP server and request an IP via a MAC?
 
Karandras69 said:
Alright that was quick. Guess my searching skillz aren't as 1337 as they used to be ;-)

Do you know how this process works? Does the DNS server request the IP from the DHCP server via a MAC address? So the DHCP server searches it's arp tables for that mac and hands out the corrosponding IP?

If that is the way it works how do I setup BIND name.conf to look at the DHCP server and request an IP via a MAC?
Click to expand...

Im honestly not too sure man, ive never done it before.. just read about it. Plus ive never used BIND before, always used MS DNS internally:(

EDIT: Did you notice this part of the article, looks like its done on the core router
update dns

To dynamically update the Domain Name System (DNS) with address (A) and pointer (PTR) Resource Records (RRs) for some address pools, use the update dns command in global configuration mode. To disable dynamic updates, use the no form of this command.

update dns [both | never] [override] [before]

no update dns [both | never] [override] [before]
Syntax Description
 
Well I'll ask him about it cause I dunno either. Thanks for the link, I'm sure it will come in handy later.
 
We use Bind 9 with ISC DHCP on our ISP network, it's been a LONG time since I set this up, I remember it being somewhat of a pain but here is how I remember it working. We currently have something like 300 subnets across 75 Class C's all doing Dynamic DNS updates for IP phones and our customer prem equipment, it works pretty nice for us, saves me from having to remember IP addresses for everything(course I have to remember the name of

You create a TSIG key on your DNS server, in ISC DHCP you then put the TSIG key into your dhcpd.conf file, the TSIG key allows your DHCP server to authenticate with your DNS server and send updates. You specify the domain's that you want to send updates to in your dhcpd.conf file. In your dns config you put the same keys specify for the same domains that you had in dhcp.conf to allow updates from your dhcp server.

Here is a website I just found, seems to outline it pretty well: http://www.mattfoster.clara.co.uk/ddns.htm

Good luck! I personally would recommend ISC BIND/DHCP over Microsoft any day but implementation in an AD network isn't quite so simple. Our DHCP and DNS servers have been up/running for over a year now without any issues
 
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