[Pdns-users] Return answer according to availability of a server

[Riccardo Brunetti]

Hello.

I will have a look at LUA records.

Thank you all for your help.

Riccardo


26/09/2023, 19:51 Victor Hugo dos Santos ha scritto:

> BTW,
> 
> 
> 
> The lua configuration will only deliver the list of the servers
> 
> available for the new queries. For example, let imagine you have the 3
> 
> registers www and a TTL of 1 hour:
> 
> 
> 
> - One client makes a query for the www register and will store it
> 
> locally for 1 hour
> 
> - 5 minutes later, one of your servers goes down.
> 
> - the PDNS will now only respond to the www queries with the 2
> 
> available servers/IPs.
> 
> - but the first client, will maintain the 3 IPs/servers on it cache
> 
> - the client browser will then try to connect to one of your servers,
> 
> but if it is unavailable, it will try the next one
> 
> - after 55 minutes more, the first client will ask again for the www
> 
> register and then will get only the 2 available servers/IPs.
> 
> 
> 
> So, you can reduce the TTL of the www register from 1 hour to 60 or 30
> 
> seconds and try to reduce/eliminate this "dead connection" on the
> 
> client side, "but" with these change you will increase the queries
> 
> that the clients are doing to the DNS servers. ;-/
> 
> 
> 
> you need to pick one !! :-D
> 
> 
> 
> Salu2
> 
> 
> 
> On Tue, 26 Sept 2023 at 19:37, Victor Hugo dos Santos
> 
> <listas.vhs at gmail.com> wrote:
> 
> >
> 
> > Hello there,
> 
> >
> 
> > you mean, something like this:
> 
> > https://doc.powerdns.com/authoritative/lua-records/index.html
> 
> >
> 
> > Anyway, you don't need it for http protocol, because it is included by
> 
> > default in almost all the browsers (rfc8305 if I remember well), so,
> 
> > you only need to create the registers:
> 
> >
> 
> > www IN A 1.1.1.1.1
> 
> > www IN A 2.2.2.2.2
> 
> > www IN A 3.3.3.3.3
> 
> >
> 
> > and it will create a round robin for you on the DNS server and if the
> 
> > web server on 1.1.1.1 is down, the client will automatically use the
> 
> > others servers.
> 
> >
> 
> > Note: There is a small performance, because the browser will need to
> 
> > contact the next server if the first is down.
> 
> >
> 
> > Salu2
> 
> >
> 
> > On Tue, 26 Sept 2023 at 18:43, Riccardo Brunetti via Pdns-users
> 
> > <pdns-users at mailman.powerdns.com> wrote:
> 
> > >
> 
> > > Hello everybody.
> 
> > > I'm trying to figure out if it is possible to make pdns (or dnsdist) to return a different answer according to the availability of a service.
> 
> > > Suppose we have:
> 
> > >
> 
> > > - server A with IP: XXX.XXX.XXX.XXX
> 
> > > - server B with IP: YYY.YYY.YYY.YYY
> 
> > >
> 
> > > Server A and B are two web servers which are configured to answer to a given http GET like http://myservice.net.
> 
> > > They are both configured in the same way and are independent.
> 
> > >
> 
> > > I would like the DNS query to return XXX.XXX.XXX.XXX as long as the server A is working (returns 200 to the GET) or return YYY.YYY.YYY.YYY when server A is not working.
> 
> > > In other words, I would like to have two records A for myservice.net with a somehow "intelligent" behavior and not a simple round-robin.
> 
> > >
> 
> > > Can you suggest me how to achieve this, if it's possible?
> 
> > >
> 
> > > Thanks a lot
> 
> > > Riccardo
> 
> > >
> 
> > >
> 
> > > _______________________________________________
> 
> > > Pdns-users mailing list
> 
> > > Pdns-users at mailman.powerdns.com
> 
> > > https://mailman.powerdns.com/mailman/listinfo/pdns-users
> 
> >
> 
> >
> 
> >
> 
> > --
> 
> > --
> 
> > Victor Hugo dos Santos
> 
> > http://www.vhsantos.net
> 
> > Linux Counter #224399
> 
> 
> 
> 
> 
> 
> 
> --
> 
> --
> 
> Victor Hugo dos Santos
> 
> http://www.vhsantos.net
> 
> Linux Counter #224399


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