There is no software anywhere that would ever do a DNS lookup before
each packet in a TCP connection. For one thing, that would be just
ridiculously expensive, at least doubling the number of packets being
sent out, and imposing huge delays as the application waits for the DNS
response. For another, once a TCP connection is established, all packets
must necessarily be between the same IP addresses. A "connection" is
defined by an address/port pair on each end. If you change any of those,
it's not the same connection anymore. Thirdly, once a connection has
been established, the system kernel typically handles all the low-level
packet sending, not the application. So, it really wouldn't make sense
to have an option that controls DNS querying between packets for a
single connection.
As Diego indicated, wget caches DNS values by default, to enhance
efficiency. If this is not the behavior you desire, you should use the
--no-dns-cache option.
...However, I think your point that wget ought "to do everything it can"
to succeed in reestablishing connection is a valid one. In the situation
you've described, it's not possible for wget to avoid losing the initial
connection, but if it fails in its second attempt, it should possibly
attempt a DNS lookup. I'll go ahead and confirm this bug (I'm actually
the upstream maintainer… as of yesterday!). I'll set the priority low,
though, as there is a simple workaround (--no-dns-cache), and I have
other things that will keep me busy for a while. :)
** Changed in: wget (Ubuntu)
Importance: Undecided => Low
Assignee: (unassigned) => Micah Cowan
Status: New => Triaged
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wget doesn't redo DNS lookup
https://bugs.launchpad.net/bugs/84104
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