Possible to config DNS to go to 2nd WWW server when primary server down?

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by Adam Ho » Sat, 30 Dec 1995 04:00:00



Hi,

I currently have a Virtual Web Server account with a company that,
generally, provides a good service.  However, there are occasions when
their Internet connection dies for a day which is not good for my
business.

What I would like to do is to have a 2nd virtual server account with
another provider - the content of which mirrors that of my primary
server.  Is it possible with DNS to have a lookup performed on the
hostname www.foo.com look to the IP address of the 1st virtual
account, and if there is no response (ie. server dead) it goes to the
IP address of the 2nd virtual account?

I don't know enough about DNS to know whether this is possible.  Has
anybody configured something like this or know of anybody that has.
How could I go about setting something like this up?

Many thanks in advance and a happy new year to all!


 
 
 

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by David-Michael Linc » Sat, 30 Dec 1995 04:00:00



> Hi,
> I currently have a Virtual Web Server account with a company that,
> generally, provides a good service.  However, there are occasions when
> their Internet connection dies for a day which is not good for my
> business.
> What I would like to do is to have a 2nd virtual server account with
> another provider - the content of which mirrors that of my primary
> server.  Is it possible with DNS to have a lookup performed on the
> hostname www.foo.com look to the IP address of the 1st virtual
> account, and if there is no response (ie. server dead) it goes to the
> IP address of the 2nd virtual account?
> I don't know enough about DNS to know whether this is possible.  Has
> anybody configured something like this or know of anybody that has.
> How could I go about setting something like this up?
> Many thanks in advance and a happy new year to all!


It is possible and common practice for gateway systems to ahve a name
resolution query reutrn several IP addresses, but if this will result in
the behavior you desire is a question of the browser implementation.

dave

--
David-Michael Lincke    Institute for Information Management at USG

URL: http://www-iwi.unisg.ch/about/team/dal.html

 
 
 

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by Adam Ho » Tue, 02 Jan 1996 04:00:00




>> Hi,
>> I currently have a Virtual Web Server account with a company that,
>> generally, provides a good service.  However, there are occasions when
>> their Internet connection dies for a day which is not good for my
>> business.
>> What I would like to do is to have a 2nd virtual server account with
>> another provider - the content of which mirrors that of my primary
>> server.  Is it possible with DNS to have a lookup performed on the
>> hostname www.foo.com look to the IP address of the 1st virtual
>> account, and if there is no response (ie. server dead) it goes to the
>> IP address of the 2nd virtual account?
>> I don't know enough about DNS to know whether this is possible.  Has
>> anybody configured something like this or know of anybody that has.
>> How could I go about setting something like this up?
>> Many thanks in advance and a happy new year to all!

>It is possible and common practice for gateway systems to ahve a name
>resolution query reutrn several IP addresses, but if this will result in
>the behavior you desire is a question of the browser implementation.
>dave

Any idea how I would go about actually configuring something like this
though?  Is it really to do with the browser anyway or is it lower
level (eg. winsock on a PC)?

Cheers,

Adam.

 
 
 

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by David-Michael Linc » Wed, 03 Jan 1996 04:00:00





> >> Hi,
> >> I currently have a Virtual Web Server account with a company that,
> >> generally, provides a good service.  However, there are occasions when
> >> their Internet connection dies for a day which is not good for my
> >> business.
> >> What I would like to do is to have a 2nd virtual server account with
> >> another provider - the content of which mirrors that of my primary
> >> server.  Is it possible with DNS to have a lookup performed on the
> >> hostname www.foo.com look to the IP address of the 1st virtual
> >> account, and if there is no response (ie. server dead) it goes to the
> >> IP address of the 2nd virtual account?
> >> I don't know enough about DNS to know whether this is possible.  Has
> >> anybody configured something like this or know of anybody that has.
> >> How could I go about setting something like this up?
> >> Many thanks in advance and a happy new year to all!

> >It is possible and common practice for gateway systems to ahve a name
> >resolution query reutrn several IP addresses, but if this will result in
> >the behavior you desire is a question of the browser implementation.
> >dave
> Any idea how I would go about actually configuring something like this
> though?  Is it really to do with the browser anyway or is it lower

Just put an A record several times into your zone file each time with a
different IP address assigned.
On the client side gethostbyname() will return a hostent structure, which
will contain an array of all the addresses assigned to that name. Now a lot
of software always just takes the first address and if it doesn't work
gives up...so it will depend on the browser code.

dave

--
David-Michael Lincke    Institute for Information Management at USG

URL: http://www-iwi.unisg.ch/about/team/dal.html

 
 
 

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by Jon Zee » Thu, 04 Jan 1996 04:00:00


Hey, browser authors, are you listening?  The web needs to be more reliable
and this is one way to improve it.

Quote:>Unfortunately, while having several A records in your zone file with different
>IP addresses will not break anything, I do not know of _ANY_ major browser
>that will try the other addresses if it cannot reach the first address given.

>I've noted this lack last year, and the year before- It's been a minor

--
   Corporate WWW Development and Hosting & the Branch Mall

(313) 741-4442  http://branch.com/              gopher branch.com
 
 
 

Possible to config DNS to go to 2nd WWW server when primary server down?

Post by Kevin Kad » Thu, 04 Jan 1996 04:00:00


Quote:>> >> What I would like to do is to have a 2nd virtual server account with
>> >> another provider - the content of which mirrors that of my primary
>> >> server.  Is it possible with DNS to have a lookup performed on the
>> >> hostname www.foo.com look to the IP address of the 1st virtual
>> >> account, and if there is no response (ie. server dead) it goes to the
>> >> IP address of the 2nd virtual account?
...
>> >It is possible and common practice for gateway systems to ahve a name
>> >resolution query reutrn several IP addresses, but if this will result in
>> >the behavior you desire is a question of the browser implementation.

In fact, this works very well with most telnet and ftp programs.

Quote:>> Any idea how I would go about actually configuring something like this
>> though?  Is it really to do with the browser anyway or is it lower

Unfortunately, while having several A records in your zone file with different
IP addresses will not break anything, I do not know of _ANY_ major browser
that will try the other addresses if it cannot reach the first address given.

I've noted this lack last year, and the year before- It's been a minor
annoyance for quite some time, though not quite annoying enough for me to
hack it into X-mosaic :)

Quote:>Just put an A record several times into your zone file each time with a
>different IP address assigned.
>On the client side gethostbyname() will return a hostent structure, which
>will contain an array of all the addresses assigned to that name. Now a lot
>of software always just takes the first address and if it doesn't work
>gives up...so it will depend on the browser code.

One thing you can do to distribute the load amongst two or more mirrors is to
use 'round robin' IP addressing, where the DNS server returns the list of
addresses shifted by one each time- so different remote users will get a
different address first, and access a different server. This doesn't gain you
much since the instantaneous hit rate from a single Netscape client grabbing
all the images in parallel has more of a impact than the average hits/second.