Bind Reverse DNS

Discussion in 'General' started by Donno, Jan 22, 2019.

  1. Donno

    Donno Member

    I have 2 DNS Severs : = HostIP1 = HostIP2
    when i do reverse lookup i get: -> HostIP1 -> HostIP2
    So far so good !
    Now i add clients and point the client to host name server, add A records and all everything works fine.
    When i do a reverse check on using mxtoolbox i get error:

    Invalid SuperTool Syntax
    Invalid Input. ptr requires a IP Address and is a Fully Qualified Domain Name.

    Should ptr records be created for all clients as well ?
  2. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    That is not reverse lookup. Reverse is when input IP-address and get the host name.
    My quess is MXtoolbox complains about the mail server IP-address not having PTR record.
  3. Donno

    Donno Member

    Thanks ! Redone test with ip and i get
    HostIP1 ->
    HostIP2 ->

    I have no PTR Records setup do need to set it up for my host domain and clients domain ?
  4. Taleman

    Taleman Well-Known Member HowtoForge Supporter

  5. Donno

    Donno Member

    Hi thanks for the link i have read it through and have some questions. The reason that i looked into the reverse ip is because i am having some mail server issues :
    [Reverse IP] points to and not
    The article says i must create new zone if my ip was [octets1].[octets2].[octets3].[octets4] then i create

    SOA [octets3].[octets2].[octets1]
    NS [octets3].[octets2].[octets1]
    PTR [octets4]

    my and uses the same ip ?
  6. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    The tutorial tells how to create a zone for reverse DNS, but also says this works only inside your own local area network using RFC 1918 IP-addresses. So don't care about that if your mail server should be acceccible from the public Internet.
    There is a question mark in the end, but the sentence is a statement. Could you formulate that as a question or remove the question mark.
    To get the PTR record for your mail server IP-address to point to your mail server hostname, contact the party that gave you that IP-number. Ask them to fix the PTR record.
  7. Donno

    Donno Member

    Yeah the question mark is there to validate the statement if it is true or not. Came right thank you :)
  8. Jesse Norell

    Jesse Norell ISPConfig Developer Staff Member ISPConfig Developer

    Both and can have the same ip address (A record, a forward lookup); the ip address itself can only resolve to a single name (PTR record, a reverse lookup). Make sure the name obtained from a reverse lookup has an A record pointing to that ip (forward confirmed reverse dns lookup - ie. the two match). You will have delivery problems to some mail systems without forward confirmed reverse lookups. You can have better mail delivery if the PTR points to the same name you use in your MX records, and your mail server identifies itself with that name (eg.

    That's the key, your server is probably not involved in handling reverse DNS if you only have a single ip address. But it could be, you just need to check with your ISP/VPS provider/whomever assigned you the ip address(es).
  9. rsteuer

    rsteuer Member

    Jesse is correct. Keeping this as uncomlicated an answer as possible, your ISP will handle reverse lookups, as the IPs are actually still with the ISP. Contact them and ask them to create reverse lookups for the IPs you are using and all will work just fine.

    We have a C block of IPs and the ISP handles numerous reverse entries for us.

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