Service Availability with SRV Record

[mark]

Archived from groups: microsoft.public.win2000.dns (More info?)

I was reading a book "DNS on Windows 2000" 2nd Edition by Matt Larson &
Cricket Liu regarding SRV Record. It mentioned something to the fact that if
I were to add 2 SRV Records for Server1 (www.domain.com) and
Server2(www2.domain.com) both with port 80 available, that if Server1 is
unavailable that requests will get sent to Server2. Does this mean that if I
were to take Server1 down, the DNS will know it is not available and direct
any new requests for www.domain.com and send them to www2.domain.com?

Thanks in advance.

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

srv records currently have one drawback - current INET clients such as IE,
ftp, telnet, ping, etc, don't understand them. There are a few one offs
that do, but not the masses yet. Even the OS apis don't allow you to query
for them directly without custom code. Instead of GetHostByName, they also
need GetSrvByName so clients can start programming for them. Short answer
is, you can't really use them yet for this purpose (unless you write your
own solution as ms did with ad resolver logic, etc.) HTH

--
William Stacey, MVP

"Mark" <Mark@discussions.microsoft.com> wrote in message
news:B4600759-2516-4D13-808A-D76B11ABE138@microsoft.com...
> I was reading a book "DNS on Windows 2000" 2nd Edition by Matt Larson &
> Cricket Liu regarding SRV Record. It mentioned something to the fact that
if
> I were to add 2 SRV Records for Server1 (www.domain.com) and
> Server2(www2.domain.com) both with port 80 available, that if Server1 is
> unavailable that requests will get sent to Server2. Does this mean that
if I
> were to take Server1 down, the DNS will know it is not available and
direct
> any new requests for www.domain.com and send them to www2.domain.com?
>
> Thanks in advance.

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

In news:uUhXnpBmEHA.3968@TK2MSFTNGP11.phx.gbl,
William Stacey [MVP] <staceywREMOVE@mvps.org> made a post then I commented
below
> srv records currently have one drawback - current INET clients such
> as IE, ftp, telnet, ping, etc, don't understand them. There are a
> few one offs that do, but not the masses yet. Even the OS apis don't
> allow you to query for them directly without custom code. Instead of
> GetHostByName, they also need GetSrvByName so clients can start
> programming for them. Short answer is, you can't really use them yet
> for this purpose (unless you write your own solution as ms did with
> ad resolver logic, etc.) HTH
>

I remember about a month ago there was a big discussion about this in the
microsoft.public.windows.server.dns newsgroups about when, if at all, the
Microsoft will implement this for IE. The outcome of the discussion is,
IIRC, that it was to be sometime in the future, but when, who knows...


--
Regards,
Ace

Please direct all replies ONLY to the Microsoft public newsgroups
so all can benefit.

This posting is provided "AS-IS" with no warranties or guarantees
and confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft Windows MVP - Windows Server - Directory Services

Security Is Like An Onion, It Has Layers
HAM AND EGGS: A day's work for a chicken;
A lifetime commitment for a pig.
--
=================================

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

I wonder why. It is pretty easy. It must be as even I have done it. Now
with the http web control in VS 2005, I could create a ~close IE clone that
uses srv records. I will wait to Beta2, as Beta1 has too many bugs yet
(imho.) Keep you posted.

--
William Stacey, MVP

"Ace Fekay [MVP]"
<PleaseSubstituteMyActualFirstName&LastNameHere@hotmail.com> wrote in
message news:#9M1KdEmEHA.1152@TK2MSFTNGP11.phx.gbl...
> In news:uUhXnpBmEHA.3968@TK2MSFTNGP11.phx.gbl,
> William Stacey [MVP] <staceywREMOVE@mvps.org> made a post then I commented
> below
> > srv records currently have one drawback - current INET clients such
> > as IE, ftp, telnet, ping, etc, don't understand them. There are a
> > few one offs that do, but not the masses yet. Even the OS apis don't
> > allow you to query for them directly without custom code. Instead of
> > GetHostByName, they also need GetSrvByName so clients can start
> > programming for them. Short answer is, you can't really use them yet
> > for this purpose (unless you write your own solution as ms did with
> > ad resolver logic, etc.) HTH
> >
>
> I remember about a month ago there was a big discussion about this in the
> microsoft.public.windows.server.dns newsgroups about when, if at all, the
> Microsoft will implement this for IE. The outcome of the discussion is,
> IIRC, that it was to be sometime in the future, but when, who knows...
>
>
> --
> Regards,
> Ace
>
> Please direct all replies ONLY to the Microsoft public newsgroups
> so all can benefit.
>
> This posting is provided "AS-IS" with no warranties or guarantees
> and confers no rights.
>
> Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
> Microsoft Windows MVP - Windows Server - Directory Services
>
> Security Is Like An Onion, It Has Layers
> HAM AND EGGS: A day's work for a chicken;
> A lifetime commitment for a pig.
> --
> =================================
>
>

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

In news:OomITFHmEHA.3340@TK2MSFTNGP14.phx.gbl,
William Stacey [MVP] <staceywREMOVE@mvps.org> made a post then I commented
below
> I wonder why. It is pretty easy. It must be as even I have done it.
> Now with the http web control in VS 2005, I could create a ~close IE
> clone that uses srv records. I will wait to Beta2, as Beta1 has too
> many bugs yet (imho.) Keep you posted.

I believe with the recent exploits in the browser, that SRV implementation
is on the back burner. I haven't seen VS 2005 yet, but I do have a copy thru
MSDN. Just a matter if I have the time to look at it. Please do let me know.

Ace

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

cool. For the browser app itself it would truly be a few lines of code,
maybe 10. A new getsrvbyname would need to be created, but that is probably
50 lines (if that) building on existing resolver. FYI - The control in VS
is basically a very smart richtextbox with a lot of properties and methods
on it. So you put it on a blank form like a textbox and build buttons and
menus around it. Should be interesting to see how people use it. Cheers!

--
William Stacey, MVP

"Ace Fekay [MVP]"
<PleaseSubstituteMyActualFirstName&LastNameHere@hotmail.com> wrote in
message news:#834vmPmEHA.2380@TK2MSFTNGP14.phx.gbl...
> In news:OomITFHmEHA.3340@TK2MSFTNGP14.phx.gbl,
> William Stacey [MVP] <staceywREMOVE@mvps.org> made a post then I commented
> below
> > I wonder why. It is pretty easy. It must be as even I have done it.
> > Now with the http web control in VS 2005, I could create a ~close IE
> > clone that uses srv records. I will wait to Beta2, as Beta1 has too
> > many bugs yet (imho.) Keep you posted.
>
> I believe with the recent exploits in the browser, that SRV implementation
> is on the back burner. I haven't seen VS 2005 yet, but I do have a copy
thru
> MSDN. Just a matter if I have the time to look at it. Please do let me
know.
>
> Ace
>
>

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

In news:OVwI5cSmEHA.3452@TK2MSFTNGP15.phx.gbl,
William Stacey [MVP] <staceywREMOVE@mvps.org> made a post then I commented
below
> cool. For the browser app itself it would truly be a few lines of
> code, maybe 10. A new getsrvbyname would need to be created, but
> that is probably 50 lines (if that) building on existing resolver.
> FYI - The control in VS is basically a very smart richtextbox with a
> lot of properties and methods on it. So you put it on a blank form
> like a textbox and build buttons and menus around it. Should be
> interesting to see how people use it. Cheers!
>
>

Interesting, I would like to see that eventually implemented. I have to hand
it to you William, you make programming sound so easy!!
;-)

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

M> Does this mean that if I were to take Server1 down, the DNS will know
M> it is not available and direct any new requests for www.domain.com
M> and send them to www2.domain.com?

No. The DNS does not "know" anything. The fallback functionality is
implemented in the service client application, whatever that is.

 

[Guest]

Archived from groups: microsoft.public.win2000.dns,microsoft.public.windows.inetexplorer.ie6.browser,comp.protocols.tcp-ip.domains (More info?)

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
<br>
<blockquote cite="miduUhXnpBmEHA.3968@TK2MSFTNGP11.phx.gbl" type="cite">
<pre wrap="">srv records currently have one drawback - current INET clients such as IE,
ftp, telnet, ping, etc, don't understand them.
</pre>
</blockquote>
Misleading (especially in the case of <code>ping</code>).  Better
expressed: The drawbacks are <br>
<ul>
<li>that they are only currently defined for
some, not all, services; <br>
</li>
<li>that for some of those services the
definitions are <em>de facto</em>, not <em>de jure</em>; and <br>
</li>
<li>that some service client applications have yet to catch up.
</li>
</ul>
Three cases in point:<br>
<ul>
<li>Location of LDAP services via <code>SRV</code> resource records
has a <em>de jure</em> definition, and is widely used.  It's one of
the foundations of Active Directory, for example.  It's also the
cornerstone of the operation of <a
href="http://www.openldap.org./faq/data/cache/393.html">the OpenLDAP
"root" server</a>.<br>
</li>
<li>Location of HTTP services via <code>SRV</code> resource records
has <a href="http://www.anta.net./nic/draft-andrews-http-srv-01.shtml">a
<em>de facto</em>
definition</a>, but none of the major web browser or proxy HTTP server
manufacturers has actually pulled
its finger out and implemented it (despite one of them having had <a
href="http://bugzilla.mozilla.org./show_bug.cgi?id=14328">a work item
to do so</a> for 5 years already, and another of them even <a
href="http://microsoft.com./resources/documentation/windows/2000/server/reskit/en-us/tcpip/part2/tcpch05.mspx">using
<code>_http._tcp</code> resource records as examples in its
documentation</a>).</li>
<li>Location of WHOIS services via <code>SRV</code> resource records
has <a
href="http://ripe.net./ripe/mail-archives/dns-wg/2002/msg00083.html">a
<em>de facto</em> definition</a>, but most WHOIS client
applications still use the older and clunkier methods of either having
long lists of servers hardwired on millions of separate machines
(making modifying or creating a WHOIS server the same nightmare that
there used to be with <code>HOSTS.TXT</code>) or using <code>whois-servers.net.</code>
and thus relying upon a single organization and being unable to cope
with registries associated with non-top-level domains (such as <code>co.uk.</code>,
which the <code>SRV</code> resource record mechanism actually handles
quite happily, in contrast).<br>
</li>
</ul>
</body>
</html>

 

[mark]

Archived from groups: microsoft.public.win2000.dns (More info?)

Thanks for everyone's response on this issue.

"Jonathan de Boyne Pollard" wrote:

> M> Does this mean that if I were to take Server1 down, the DNS will know
> M> it is not available and direct any new requests for www.domain.com
> M> and send them to www2.domain.com?
>
> No. The DNS does not "know" anything. The fallback functionality is
> implemented in the service client application, whatever that is.
>