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CNAME and arpa entries

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  • 1.  CNAME and arpa entries

    Posted 03-26-2020 02:32
    I would like to create a CNAME entry and arpa entry into the SRX.

    In dnsmasq for dd-wrt for example...

    cname=www.example.com
    local=/192.168.1.in-addr.arpa/

    Thats in linux. I want for Junos. SRX240. Should be a common way im hoping.

    Adrian Aguinaga
    A.A.S. , B.S.C.M. ITT Tech..
    Kodos!!!!


  • 2.  RE: CNAME and arpa entries

     
    Posted 03-27-2020 02:49

    You can do this for host records.

     

    https://kb.juniper.net/InfoCenter/index?page=content&id=KB26800

     

    But I don't think there is an option for reverse dns lookups.

     



  • 3.  RE: CNAME and arpa entries
    Best Answer

    Posted 03-27-2020 20:15
    I entered a static host mapping but I thought that I read somewhere that if you set a static dns mapping that you must enter an ip. Can anyone confirm? I'm having trouble with this because the authoritative domain has a hidden ip. Thats Xfinity/comcast for you.

    I input an alias for the cname as such.

    static-host-mapping {
    hsd1.ca.comcast.net alias hsd1.ca.comcast.net;
    }
    }
    ...


    That has no ip because I cant find the ip for that domain. Help!!!!


  • 4.  RE: CNAME and arpa entries

    Posted 03-27-2020 20:22
    By the way this address won't tesolve.

    I haven't made any other entries such as nat for that address. It should resolve but it doesn't. Anyone have ideas or the ip of that domain name. Or method to find it. As well as other ways to resolve it.


  • 5.  RE: CNAME and arpa entries

    Posted 03-27-2020 21:15
    Solution was accidentally marked. Solution not accepted yet.


  • 6.  RE: CNAME and arpa entries

     
    Posted 03-28-2020 02:48

    You can only resolve names to ip addresses with SRX entries.

    You cannot reverse dns entries of ip addresses to a name.

     



  • 7.  RE: CNAME and arpa entries

    Posted 03-28-2020 03:23
    Ok, seeing how the lack of records for these type of servers says they have their standard. MX, blah, blah.

    I've been confused.

    I guess to throw a wet blanket on the whole thing I will have to grasp some understanding.

    Last question.

    I couldn't tell if the alias entry had a negative cache or positive effect. It says in the documentation that an ip might be needed.

    Any comments.

    Am I wetting the blanket, so to speak, but not throwing the blanket on the situation?

    What am I doing lol?

    Did the banklet even get wet?
    Does that entry add to the dns server wayside? Or does it get stale, or what?


  • 8.  RE: CNAME and arpa entries

     
    Posted 03-28-2020 07:47

    I'm not sure I follow the question so apologies if this is not a matching answer.  These srx records only work when the clients are using the srx as their dns server.  They create srx local answers for the specific requests on the srx.  Other dns requests are forwarded normally.

     

    Caching of answers will follow all the normal client side parameters.

     



  • 9.  RE: CNAME and arpa entries

    Posted 03-28-2020 09:49
    Thx Steve.

    I finally went in for dynamic dns.

    Solution accepted.
    😀