Newbie post - strange routing for ZA to UK via USA?
barmar at alum.mit.edu
Thu Apr 20 23:56:31 UTC 2006
In article <e28uch$1nom$1 at sf1.isc.org>,
"Phlippie Smit" <smitpf at nospam.spamfree> wrote:
> Hi there
> Could anyone please explain how routing to a website works?
> I basically need to know what happens when a site is requested by a web
> browser in one country, when the site is hosted in another. For the sake of
> the example, say the site is in the United Kingdom and the visitor is in
> South Africa.
> The way I currently understand it:
> 1. My browser interrogates my IP settings and finds a DNS server.
> 2. The DNS server "traverses" until it finds a DNS server with the
> requested site name, and converst this to an IP address.
> 3. My Computer connects to the other IP adddress.
Close enough to correct for the purposes of this discussion.
> The actual question (excuse the long intro):
> Why do some sites first go through the USA and then only to the UK (Is it a
> routing or a DNS problem)?
> I have tested the following sites from South Africa:
> www.pipex.net - goes directly to UK
> www.yell.com - goes directly to UK
> www.activitybreaks.com - goes the the USA and then to UK
> Why do some sites have more and other less "hops" to the actual www server?
Routing is not by country, it's by ISPs. Some ISPs have more
connections in different countries, so traffic can go directly from ZA
to UK. Other ISPs may not have direct connections, so traffic has to
take a more circuitous path.
> Would the strange route from South Africa to the UK slow down traffic to the
> site? (I have used NeoTrace to view the route and nodes in the path)
Probably. In general, if the round-trip time is longer (you can see
this in ping and traceroute), data transfers will usually be slower. In
the case of downloads you can mitigate this somewhat by using a TCP
tweak program to increase your RWIN.
Barry Margolin, barmar at alum.mit.edu
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