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Re: Proxies and gethostbyname

From: David W. Morris <dwm@xpasc.com>
Date: Mon, 27 Apr 1998 12:37:16 -0700 (PDT)
To: Jeffrey Mogul <mogul@pa.dec.com>
Cc: http-wg@cuckoo.hpl.hp.com, http-wg@hplb.hpl.hp.com
Message-Id: <Pine.GSO.3.96.980427122132.4948H-100000@shell1.aimnet.com>


On Mon, 27 Apr 1998, Jeffrey Mogul wrote:

>     Clarification is needed on what error is to be returned if a Proxy
>     times out looking up a hostname.  The spec is silent on what is a
>     very common failure.
> 
>     My current opinion is that returning 504 Gateway Timout is correct,
>     but that clarification to the spec is in order.  But other options
>     include introducting other error codes, or less likely, some other
>     existing error code.
>     
> Before we charge off on a detailed discussion of what to do when a
> proxy times out on a DNS translation, we might want to consider whether
> is error is part of a larger class.
> 
> For example,
> 	what if the proxy has no route to the server?  (i.e.,
> 	it gets a "host unreachable" error).  This may also
> 	be a transient error (cf. the paper in USITS '97 on
> 	the observed routing instability in the Internet).  Is
> 	this the same as a "504 Gateway Timeout"?
> 	
> I'm not sure whether there are any other errors in this class.
> But if these are the only two that we can think of, perhaps
> the proper name for the error is
> 
> 	504 Temporarily Unable to Forward Request
> 
> with an entity body that explains the reason in more detail.
> I.e., the relevant question is not "was this a timeout or not?"
> but "is the error (probably) transient or is it permanent?"
> 
> If people think that these cases are actually different enough
> to warrant separate error codes, then I think we ought to add
> a "No route to next-hop server" code if we add a "DNS timeout" code.

As I tried to say, there are more errors than just a timeout between
the proxy and the down stream server and they need to be differentiated.

Dave
Received on Monday, 27 April 1998 12:47:04 EDT

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