Net::DNS::Resolver and nameservers

henzen has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I'm slow today for some reason - maybe too little coffee, and would appreciate some wisdom.

Net::DNS::Resolver->new(nameservers => [qw(1 2 3)]...
[download]

That's the usual usage, ie, hard coding the nameserver IPs. I want to use a variable such as @nameservers (or even the scalar $nameservers):

Net::DNS::Resolver->new(nameservers => [@nameservers]...
[download]

This works, but it only queries the first nameserver. The remainder are ignored (so it fails if the first NS is dead).

I cannot hard-code as $ns = qw(ip1 ip2 ip3 ip4), since the IPs are sourced from another variable and qw() doesn't interpolate (so I cannot do $ns = qw($ip1 $ip2 $ip3 $ip4))...

I just need to programmatically pass several nameserver IPs to Net::DNS::Resolver.

Any pointers to alleviate my dumbness would be appreciated. Thanks

Comment on Net::DNS::Resolver and nameservers Select or Download Code

Replies are listed 'Best First'.
Re: Net::DNS::Resolver and nameservers by gam3 (Curate) on May 13, 2011 at 14:38 UTC
The code `Net::DNS::Resolver->new(nameservers => [qw(1 2 3)];` and the code `@nslist = qw(1 2 3); Net::DNS::Resolver->new(nameservers => [@nslist];` [download] are the same, so I think the problem with only the first DNS server being queried is a problem with the Net::DNS::Resolver package or the underlieing library. You might randomize the list of nameservers and reload them in a different order if a request fails. -- gam3 A picture is worth a thousand words, but takes 200K.	[reply] [d/l] [select]
Re^2: Net::DNS::Resolver and nameservers by henzen (Acolyte) on May 13, 2011 at 15:14 UTC
Thanks for the quick response. It looks like this was bad data ('1.1.1.1', '2.2.2.2 3.3.3.3', '...'). If 1.1.1.1 was dead, it hit '2.2.2.2 3.3.3.3' and soiled itself...	[reply]
Re: Net::DNS::Resolver and nameservers by jellisii2 (Hermit) on May 13, 2011 at 15:01 UTC
The documentation states that it takes an arrayref. Have you tried to use `Net::DNS::Resolver->new(nameservers => [\@nameservers] ...`	[reply] [d/l]
Re^2: Net::DNS::Resolver and nameservers by henzen (Acolyte) on May 13, 2011 at 15:17 UTC
Na, that makes it fail every time. Problem solved though, so thanks anyway.	[reply]
Re^2: Net::DNS::Resolver and nameservers by MidLifeXis (Monsignor) on May 13, 2011 at 18:06 UTC
`[\@foo]` is an AoA, not an arrayref. Update: Well, it is an arrayref of sorts, but not a~~n arrayref~~ reference to an array (better? ;-b) of scalars containing strings. :-) --MidLifeXis	[reply] [d/l]
Re^3: Net::DNS::Resolver and nameservers by Anonymous Monk on May 13, 2011 at 18:16 UTC
but not an arrayref of scalars. :-) An arrayref is a reference to an array is always a reference to an array, no mater what the array contains, and yes, arrayrefs , like all refs, are scalars -- tricky :)	[reply]


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