On 18/07/2019 23:08, Evgeniy Berdnikov via Exim-users wrote:
> Quite puzzling... The only difference I see here is the presence of one
> authority record in dns query from Exim, marked as [1au].
> Tcpdump man page states:
>
> A few anomalies are checked and may result in extra fields enclosed in
> square brackets: If a query contains an answer, authority records or
> additional records section, ancount, nscount, or arcount are printed as
> `[na]', `[nn]' or `[nau]' where n is the appropriate count.
>
> Running tcpdump with -vvv shows that there is an authority record for root.
> I don't know is this behaviour legal or not, and why this record is present
> in exim queries. But I propose to try two other methods to resolve name:
>
> 1: exim4 -be '${lookup dnsdb{a=smtp.gmail.com}{$value}fail}'
>
> 2: perl -e '($n,$a,$t,$l,@ip)=gethostbyname("smtp.gmail.com"); print "n=$n\na=$a\n"; for (@ip) {($w,$x,$y,$z)=unpack('W4',$_); print "$w.$x.$y.$z\n"}'
>
> In my experiments 1st variant results in additional authority record, the
> 2nd does not (as manual run of telnet). Does 1st variant fail when exim
> fails to run transport?
Might there be a dnssec-related difference? Would that show in the
text tcpdump output, or would you need to look carefully with wireshark?
--
Cheers,
Jeremy
