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Teerarat's avatar
Teerarat
Icon for Cirrus rankCirrus
Aug 21, 2017

How does client work when dns response cname to client

I have some problem, I setup F5 DNS response cname when client request dns to > cname: , I try to packet capture when dns response cname to client, I found client not resolve cname, when i try to test by use client request dns to > AD DNS > F5 DNS it's work.

 

application delivery
BIG-IP DNS
  • Stanislas_Piro2's avatar
    Stanislas_Piro2
    Icon for Cumulonimbus rankCumulonimbus
    Aug 21, 2017

    Hi,

     

    Dns client will not follow cname. It send a request and expect a response including all information required.

     

    The dns forwarder (AD) will request his forwarder or root servers.

     

    If the AD uses a forwarder, it works as a dns client, else, it read response and follow NS, CNAME.. until it receive an error or the expected answer (ex : ip address of the resource)

     

    When it get it, it reply to the dns client.