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Re: Can't connect to Web

Cross-posted to 3 groups.

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On Wed, 31 May 2017 17:51:05 -0000 (UTC), Bert <bert@iphouse.com> wrote:

>In news:oghre5$1ctf$1@gioia.aioe.org Stef <not@this.address.com> wrote:
>
>> But even when I enter the server "name," I think my email and ftp
>> clients lookup the IP address on first access and store them for
>> future use, so it doesn't have to look it up each time
>
>If they do, it's a bad idea. 

Agreed. Thanks to DNS, if a remote host's IP address needs to change for
any reason, DNS will automatically find the new IP.

>Many large-scale systems (and some small ones) have multiple IP
>addresses and rotate the way they appear to DNS requests in order to
>balance user load. 

Typically referred to as "DNS load balancing", it's a free but very
crappy way to make a remote service available. Fortunately, it's pretty
rarely used these days. Instead, most publicly accessible organizations
use actual load balancers, where a remote FQDN resolves to a single IP
address that's configured on the client side of a load balancer. The
actual application servers reside behind the load balancer where they
can't be accessed directly by the public.

>They'll also take addresses out of rotation if systems are down.

The main problem with DNS load balancing (simply adding additional A or
AAAA records for a given FQDN) is that DNS has no way to do application
health checks, so regardless of whether a specific server is up or not,
DNS will happily hand out its IP address. Real load balancers address
that issue by performing periodic application health checks, taking
servers out of rotation if they don't respond properly and then adding
them back into rotation when they start responding again.

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Thread

Can't connect to Web Steve Hayes <hayesstw@telkomsa.net> - 2017-05-26 10:04 +0200
  Re: Can't connect to Web rickman <gnuarm@gmail.com> - 2017-05-26 04:47 -0400
    Re: Can't connect to Web Steve Hayes <hayesstw@telkomsa.net> - 2017-05-28 06:21 +0200
      Re: Can't connect to Web VanguardLH <V@nguard.LH> - 2017-05-27 23:33 -0500
      Re: Can't connect to Web rickman <gnuarm@gmail.com> - 2017-05-28 01:24 -0400
        Re: Can't connect to Web Paul <nospam@needed.invalid> - 2017-05-28 02:17 -0400
          Re: Can't connect to Web rickman <gnuarm@gmail.com> - 2017-05-28 03:18 -0400
            Re: Can't connect to Web VanguardLH <V@nguard.LH> - 2017-05-28 05:31 -0500
  Re: Can't connect to Web VanguardLH <V@nguard.LH> - 2017-05-26 13:39 -0500
  Re: Can't connect to Web Stef <not@this.address.com> - 2017-05-28 17:16 +0000
    Re: Can't connect to Web Bert <bert@iphouse.com> - 2017-05-28 17:48 +0000
      Re: Can't connect to Web Stef <not@this.address.com> - 2017-05-29 19:05 +0000
        Re: Can't connect to Web Bert <bert@iphouse.com> - 2017-05-31 17:51 +0000
          Re: Can't connect to Web Stef <not@this.address.com> - 2017-05-31 23:03 +0000
          Re: Can't connect to Web Char Jackson <none@none.invalid> - 2017-06-13 15:10 -0500
    Re: Can't connect to Web VanguardLH <V@nguard.LH> - 2017-05-28 15:11 -0500
      Re: Can't connect to Web rickman <gnuarm@gmail.com> - 2017-05-29 00:20 -0400
      Re: Can't connect to Web Stef <not@this.address.com> - 2017-05-29 18:57 +0000
    Re: Can't connect to Web Steve Hayes <hayesstw@telkomsa.net> - 2017-05-29 03:53 +0200
      Re: Can't connect to Web Stef <not@this.address.com> - 2017-05-29 16:27 +0000
      Re: Can't connect to Web VanguardLH <V@nguard.LH> - 2017-05-31 15:41 -0500
        Re: Can't connect to Web Steve Hayes <hayesstw@telkomsa.net> - 2017-06-01 08:52 +0200
          Re: Can't connect to Web Rene Lamontagne <rlamont@shaw.ca> - 2017-06-20 20:50 -0500

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