WWW failover me DNS

[Giorgos Keramidas]

On 2005-07-12 11:38, Polychronis Ypodimatopoulos <pol at entelia.gr> wrote:
> Sto proigoumeno mail aneferes oti peftei ena mixanima (theos
> sxoresto!) To link gia to GSLB einai polu endiaferon alla anaferetai
> se whole site failovers. Auto einai polu polu diaforetiko kai
> suntheto.  An omos to problima sou einai na upostirikseis ena server
> me ena backup server kai oi duo autoi briskontai piso apo ena NAT pou
> eksipiretei to domain 1-2-3-4.gr tote i katastasi aplopoieitai polu!
> 
> Basika, stin periptosi auti to dns caching problima pou anaferei to
> GSLB den ufistatai pleon opou kai an vrisketai o dns (piso i mprosta
> apo to NAT) kai tha mporousa na sou eksigiso giati.  Se mia toso apli
> periptosi omos de xreiazesai kan to GSLB mias kai o backup server tha
> mporouse aplos na kanei polling pano ston primary kai na parei ti
> thesi tou molis ton brei na upoferei apo sundromo "down". Enas
> ping-based polling mechanism einai arketos se sunduasmo me mia
> ifconfig gia na "foreseis" tin IP tou "ekleipontos" primary server.
> Kodika gia to polling mporo na sou steilo, an kai eimai sigouros oti
> tha ton breis/grapseis polu eukola.

Pos "epanerxetai" o kanonikos server otan shkw8ei pali?

To "failover" pou perigrafeis den einai pote toso aplo oso ena
ping-based ifconfig loop :)