Date: Sat, 6 Jun 2009 22:44:38 -0600 From: Tim Judd <tajudd@gmail.com> To: Peter <fbsdq@peterk.org> Cc: freebsd-questions <freebsd-questions@freebsd.org> Subject: Re: /etc/hosts - how does that file work?? - was weird nfs issues. Message-ID: <ade45ae90906062144m3a08f892ubeef1367dc7f259f@mail.gmail.com> In-Reply-To: <5359c8a6e4fc10bf951a7ee095b0d29f.squirrel@webmail.pknet.net> References: <5359c8a6e4fc10bf951a7ee095b0d29f.squirrel@webmail.pknet.net>
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On 6/4/09, Peter <fbsdq@peterk.org> wrote: >> On Thursday 04 June 2009 20:48:21 Peter wrote: >>> iH, >>> This all started with NFS not mounting at boot....so, testing in VMs: >> >> <snip> >> >>> Why is ping using one IP, and ssh/mount_nfs/showmount using another IP > from /etc/hosts? >> >> Q: Where is described that name resolution for A or PTR records should > be >> returned in a fixed order and that a consumer should always use the > first >> one >> returned? >> A: Nowhere. Name servers are encouraged to do round-robin returns if not > specified otherwise. Applications may sort/pick at their own leisure. >> >> -- >> Mel > > I do not think /etc/hosts does round robin, I always assumed first match > wins...DNS/bind I would understand... > > Why does ping always return the 172.20.6.1 address, > and ftp,nc,ssh,telnet,fetch _always_ uses the 116 address? > > I would assume at least sometimes it would hit the 172 address with > anything besides ping - but it only ping hits the 172 address... > If so, I'd guess there would be consistency between ping lookups and > 'telnet/ssh/etc' lookups... > > Why if the 116.23.45.3 last octet is bumped up, everything _always_ > returns the 172 address? > > client# grep server /etc/hosts > 172.20.6.1 server.test server > 116.23.45.5 server.test server > client# telnet server > Trying 172.20.6.1... > telnet: connect to address 172.20.6.1: Connection refused > Trying 116.23.45.5... > > /etc/hosts - 'server' changed to > 116.23.45.3: > > client# telnet server > Trying 116.23.45.3... > telnet: connect to address 116.23.45.3: Operation timed out > Trying 172.20.6.1... > telnet: connect to address 172.20.6.1: Connection refused > telnet: Unable to connect to remote host > > if server has ip>116.23.45.3, it always uses the 172 address first... > > but ping always uses the 172... > even if third entry is added into /etc/hosts - nothing ever uses it as the > first/primary IP. > > Is there an algorithm based on IP/program being used and the returned IP? > I can't sit and watch this thread anymore. Something itchin' to say: DNS, who can handle multiple A records in an optional round-robin design, is perfectly fine to assign multiple A records to a resource. /etc/hosts, which as always existed (back when the Internet was created/new), was a unique record source only. Having oddities in /etc/hosts is expected IMHO when a "mistake" like multiple resources assigned different records. What's to stop you from creating slightly different records in /etc/hosts? Whats to stop you from hitting 'privserver' and 'pubserver', for private and public IPs respectively. why are you so hung up on dual IPs for a single host? would dnsmasq provide a solution to dual A records for one resource? I'll help, when I can. but forcing this on /etc/hosts is a dead end.
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