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Thread: DHCP and DDNS

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  1. #1
    Just Joined!
    Join Date
    Feb 2011

    DHCP and DDNS

    Hola all! This is my first post here and I have been searching for a solution for some time now. Hoping someone can provide an answer.

    Our current internal network at the workplace is running DHCPD (on centos) and running DDNS (bsd), which is working correctly; but we want to make some slight improvements.

    Currently, there are hundreds of nodes in this lab, and right now, they are all hostnamed to a location reference, and not so much to what they do. This makes the box easier to locate in such a large lab full of nodes. The problem is the users/developers cant remember the location name (it is rather long) .. so we have been making static CNAMEs, basically creating an alias such as web to alias to the long location hostname so when Bob wants to get to the "web" box, he just uses web, and not the long location hostname.

    So, what we would LIKE to do, is use simple hostnames (such as web, or ftp, etc...), but have the reverse zones give back the location hostname(so us, the admins, can locate this thing if needed). Problem is how..??

    I cant seem to find an option in the dhcp config to specify the reverse entry for a host (such as the ddns-hostname option), only the forward entry.. Anyone here know of the option, if one, or have any other ideas to make this work via ddns? It is my current understanding that ddns-rev-domainname only specifies which zone dhcpd/bind writes the entry, which seems to automagically use the forward hostname specifed in the config?


  2. #2
    Linux Guru Lazydog's Avatar
    Join Date
    Jun 2004
    The Keystone State
    I am going to assume that you are having the DHCP server update the DNS zone records. The answer is you can't. And why would you need this anyway? You said yourself that you use CNAMEs for all the systems so the clients don't have to remember the long names.

    So if client A says they are having issues on server Y then you just need to do a lookup of the short name which should give you the long name.

    You should also be aware that some security conscious programs do a reverse lookup and if the forward and reverse don't match the service is unavailable.


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  3. #3
    Just Joined!
    Join Date
    Feb 2011
    Thanks Robert.

    I'm aware of the reverse lookup issue that may arise and that some programs/services may acknowledge them as such, but since this is an internal lab for flight simulation for NASA, things are only but so logical. Since they're broke, they cant afforid AD just yet, so our windows boxes use WINS. The names on these boxes are set to the physical location as well. When developers/researchers are going through the workgroup listing, theyre seeing a location name, and to them, that means nothing.

    Ideally, what we wanted to do was to change the actual hostname on the box, as well as the wins name to a meaningful name, so the data is equal across the board (dns and wins) then set the reverse to the location. I understand its a bit unorthadox.

    I was already under the impression this wouldnt be readily possible, unless some custom programming/rigging was involved.

    If anyone else has any ideas on how this can be somewhat easily accomplished, please shed some light.


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