Also be aware that there some ISPs tend to a few things with DNS 1. Some do block access to their DNS from outside of their network. I think this is mainly because they don't want to provide a service to the wider Internet that potentially means their own customers get impacted by DNS DOS attacks or simply heavy load. Certainly Telstra did do this as their DNS became well-known in Australia.
I recently implemented a fairly large enterprise and Internet facing DNS environment for a telecommunications customer recently and the legacy environment was being impacted quite heavily by non-customer load. So while you may have some Telstra DNS server addresses, they may be being blocked from their mobile/3G network to minimise unplanned load. 2. DNS can be used to help direct the subsequent application traffic to particular managed servers. For instance, Internode provide unmetered content to their customers, one of which is the ABC iView service. However at least in some part, probably because of the use of content-delivery networks, Internode ask to make you use their DNS. I presume if you don't their is a risk that your ABC iVIew traffic gets directed to servers other than those Internode can provide unmetered traffic for, and hence you think your iView is unmetered but is in fact coming from outside servers. And as James Gray has said DNS can also be used as a poor-mans way of filtering traffic - by giving NXDOMAIN or other redirections when you try to resolve the name of an "undesired" service. (And of course hijacking legitimate DNS services, through cache poisoning and the like, is one way the bad guys can you fool you to visit them instead of your regular programmed service). Most Interrnet service providers do list what their recommended DNS is for their service. Usually you can implement your own or choose your own DNS service, but you need to be aware a little of what you are doing. Regards, Martin martinvisse...@gmail.com On Sun, Mar 28, 2010 at 5:57 AM, Ashley Maher < ashley.ma...@didymodesigns.com.au> wrote: > Thanks Martin, > > host > > damn > > That is what I was looking for. It has been years since I have needed that. > > I am used to putting in the IP of a dns server into resolv.conf and all > good. It was very frustrating to find that most of the listed tesltra > dns servers failed. > > host allowed me to check what servers are working quickly. > > Thanks. > > All good now. > > Brain Fade. > > Regards, > > Ashley > > > Martin Visser wrote: > > Ashley, > > > > Response, inline below > > > > Regards, Martin > > > > martinvisse...@gmail.com <mailto:martinvisse...@gmail.com> > > > > <snip> > > -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
