Re: [Exim] Very Slow response: exim -bt

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Author: Philip Hazel
Date:  
To: Odhiambo Washington
CC: Exim Users, ice
Subject: Re: [Exim] Very Slow response: exim -bt
On Thu, 9 Aug 2001, Odhiambo Washington wrote:

> Here now comes a better output:


For those who may not understand why the first -d9 run was very sparse:
in modern versions of Exim, you have to be an admin user to set any
debug level > 1.


> DNS lookup of mail.wananchi.com (A6) gave TRY_AGAIN
> mail.wananchi.com in dns_again_means_nonexist? no (end of list)
> returning DNS_AGAIN
> DNS lookup of mail.wananchi.com (AAAA) gave TRY_AGAIN
> mail.wananchi.com in dns_again_means_nonexist? no (end of list)
> returning DNS_AGAIN
> DNS lookup of mail.wananchi.com (A) succeeded


Presumably the delay was in those two lookups for IPv6 DNS records (A6
and AAAA). The DNS server, instead of saying "no such record" instantly,
gave a timeout. That means there is a problem with the DNS server.

Solution: recompile Exim without IPv6 support, unless you are
particularly interested in running IPv6.

[Aside: at the IETF meeting that I'm currently attending, the consensus
at a discussion of AAAA vs A6 records was to use only AAAA records, and
not to proceed with A6. So the next release of Exim will have A6 support
removed.]

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.