bad horizontal referral ?

Kevin Darcy kcd at
Wed Mar 12 03:50:49 UTC 2008

Jean-François Leroux wrote:
> Thanks for the explanation, Kevin. If I may ask, what means
> 'horizontal' in the message? I've had a look in my DNS & Bind book but
> couldn't find anything about it...
> And while I'm thinking of it, how can I know which server refers me to
> a wrong address? Is this possible ?
> 2008/3/12, Kevin Darcy <kcd at>:
>> Jean-François Leroux wrote:
>>  > Hi,
>>  > doing a trace with dig today I got a 'BAD (HORIZONTAL) REFERRAL'
>>  > message, with the correct answer though.
>>  >  What does this mean ?
>>  >
>>  >
>>  >
>> Referrals should be "down" not "across". If you're resolving
>>  iteratively and along the way a delegated nameserver for refers
>>  you to, that's a useless referral because it doesn't get you
>>  any closer to resolving the name.
>>  Dig probably got the correct answer because it gave up on the broken
>>  nameserver and tried a different one.
"Horizontal" means at the same level of the hierarchy. The DNS namespace 
is often viewed as being tree-like, with the "root" at the top and each 
level of subdomain extending downwards. If a referral is "across" rather 
than "down", it's "horizontal" instead of "vertical".

So many prepositions, so little time...

      - Kevin

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