On 20/06/2011, at 4:00 PM, Robin Belford wrote:
> Just to clarify one thing. > > John's problem is a slowdown of this internet connection. Let's call it > bandwidth. > It appears to be caused by congestion on the DSLAM at the exchange, or > perhaps a faulty joint in the local loop (copper) wiring. It could be caused > by a firmware issue in his modem/router or some of the other items listed > below. > but > No amount of changing DNS servers will fix this. You certainly will get > faster results back for a IP address lookup, or name search request, but it > won't help a slow download. > > robin Hi Robin, Yes and No. John’s problem does appear to be caused by congestion on the internet at “peak traffic” times and we are trying to get the best possible results we can for John. Hence all the testing of DNS IP Addresses, background activities happening etc. etc. I don’t agree with your comment that "No amount of changing DNS servers will fix this”. OK, it won’t fix it completely (as we don’t have a lot of control over Internet congestion), but it can help him achieve better results than he is at the moment. Virtually any time an application on your Mac does anything on the Internet—checking your email, loading a Web page, running Software Update, using Ping in iTunes, and so on—it must find the IP address of the server it wants to communicate with. To do this, it uses the domain name service (DNS): it queries a device called a domain name server, which keeps records of which domain names (such as tidbits.com) correspond to which numeric addresses (such as 184.106.219.205). If the first DNS server your Mac asks doesn’t know the address, the server queries another, and so on up a hierarchical chain leading to a small number of authoritative servers for an entire top-level domain (such as .com). This system is fairly well known, but many people don’t realize that: • A seemingly simple activity such as loading a Web page could involve a handful, or even dozens of DNS lookups. • DNS lookups take time, and must happen before any data can be transferred between your computer and the server. So, the more DNS lookups that must take place, and the longer each one takes, the longer you must wait for the connection to become active. • Some DNS servers are much faster than others. • You’re not stuck with the DNS servers your ISP tells you to use—you have complete freedom to choose! Every ISP provides DNS servers—they may give you addresses to enter manually when setting up your Mac and other devices, or they may use a dynamic method, such as DHCP, to automatically tell your Mac which DNS servers to use. Either way, you may override this choice if your ISP’s DNS servers don’t perform as well as you’d like. This is why we are using “namebench” (among other testing, if you have been following the thread) to test this and find out for sure how fast John’s DNS servers are—and whether there might be an alternative? It is time consuming & frustrating trying to locate where the bottleneck is and what is causing it. But we are getting better results than John was originally experiencing and hope to get better with more testing. Cheers, Ronni 17" MacBook Pro 2.3GHz Quad-Core i7 “Thunderbolt" 2.3GHz / 8GB / 750GB @ 7200rpm HD OS X 10.6.7 Snow Leopard Windows 7 Ultimate (under sufferance) -- The WA Macintosh User Group Mailing List -- Archives - <http://www.wamug.org.au/mailinglist/archives.shtml> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml> Unsubscribe - <mailto:[email protected]>
