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Proper format for PTR entries

Discussion in 'General Discussion' started by ne0shell, Nov 22, 2003.

  1. ne0shell

    ne0shell Well-Known Member

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    I have been delegated authority for all of my IP's by my host and need to know the proper format to enter a PTR record using the DNS entry editor in WHM. Would it be :
    sub.domain.com. PTR 123.12.12.12

    or

    sub. PTR 123.12.12.12 ?

    I have gotten advise for variations on both and need to be sure as we will be handling reverse authority for a very large number of domains via cPanel.

    Also - assuming all the DNS entries are correct such as NS and A records, will the PTR entry be enough to provide reverse resolution for mail and IRC type operations?

    Thanks,
    Neoshell
     
  2. shaun

    shaun Well-Known Member

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    PTR can be confusing...

    say you had ip 1.2.3.4 and wanted it pointed to 1-2-3-4.domain.com


    4.3.2.1 IN PTR 1-2-3-4.domain.com.

    Notice the ip is backwards!


    Also you need to create a seperate zone for them...

    zone: 3.2.1.in-addr.arpa

    so really your record would look like this inside that zone file..

    4 IN PTR 1-2-3-4.domain.com.
     
  3. SarcNBit

    SarcNBit Well-Known Member

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    Using 1.2.3.4 for the IP and 1-2-3-4 for the hostname is liable to confuse the majority of people reading this thread for support.
     
  4. sv1

    sv1 Well-Known Member

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    I'm retarded when it comes to this can someone please post the exact steps to doing this?

    and the 1.2.3.4 did not confuse me... ;-)
     
  5. SarcNBit

    SarcNBit Well-Known Member

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    Are you sure about that ;-)
     
  6. sv1

    sv1 Well-Known Member

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    thanks for your help....

    anyone else?
     
  7. sv1

    sv1 Well-Known Member

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    edit was done in:
    /var/named
     
  8. ne0shell

    ne0shell Well-Known Member

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    I was able to get this working perfectly with the help of a DNS tutorial on a friends web site. cPanel changes things just a little bit but with some edits and the right guide its possible.
    I keep meaning to set aside the time to do a tutorial on this, maybe while everyone is hungover tomorrow I can get something done.

    you need to add a record in /etc/named.conf for your ip allocation. So if you have ips 1.2.3.4 through 1.2.3.9 you would add:

    zone "3.2.1.in-addr.arpa" IN {
    type master;
    file "/var/named/3.2.1.db";
    allow-update { none; };

    (notice the last number of the ips are not in the record and that the entry points BIND to a file named :"3.2.1.db" in
    var/named/

    of course you need the db file which the bottom part looks like:

    )
    IN NS ns1.mydomain.com.
    1 IN PTR ns1.mydomain.com.
    2 IN PTR some.domain.com.

    (Ive skipped the normal entry at the top which lists the domain, refresh, name server and responsible party)

    as you can see each last number in the ip gets a PTR entry which points to the domain on its IP. You would have an entry for each IP using just the last integer.

    make your changes, do a BIND restart and use an online DNS tool to check for PTR records. Dong this lets you visually see the trace down the 4 digits of a class C ip and will tell you if the trail is stopped anywhere (like the party who was to have assigned your nameserver teh ability to do PTR records).

    I know this is very limited, hopefully it will help point someone in teh right direction, (be sure to notice the . at the end of all the domain names in the PTR record, it wont work without them)

    I'll try to do a visual and more in depth how - to soon.

    neoshell
     
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