Hi Dave, Comments below. At 07:20 PM 1/5/02 -0500, you wrote: > > From: Julian Opificius <[EMAIL PROTECTED]> > > > > In response to Dave Reeds post ... > > > > Well, in the absence of a response by a guru, here's the scoop on > > forwarding ... > > > > Forwarding was intended to be used in larger networks where there are > > multiple names servers. To minimize traffic to the "big cloud" one server > > is nominated as a local master, and all other servers send their requests > > to the forwarding server, wait a while, then go to the main upstream > > servers themselves (which would happen if the forwarding server went > down). > > Assuming the forwarding server is functioning, it will cache the > results of > > resolves for subsequent reuse for other local requests, thus minimizing > > traffic to the outside world. > > > > Note that the according to the design philosophy, forwarding server is > > intended to be on your own network. > > >My ISP's nameserver is the closest on my network - correct?
Well he's not on your "network" in the practical sense that you have to connect somehow to get to him, though obviously you're on his by virtue of your connection. Again, the forwarding issue was for larger networks where maybe five nameservers all might separately ask for resolution of the same name - say www.microgrinch.com. With a forwarding nameserver, the designated forwarder on your LOCAL network would do the lookup once, and cache it for all the other servers. Get it? > > In my case (and I suspect in yours), there is only one DNS machine. This > > means that there is no concept of concentrating DNS calls through one > > caching server, because there IS only one server. > > If you set your own DNS server up to treat the upstream server as a > > forwarding server (note the wording!), then it will do exactly what it > > would do anyway, because there is no other LOCAL server for it to go to > > first. Which means your configuration will work :-) > > > > <major clipage> > > > > Julian. > > >Hmm, where are you quoting from? O'Reilly. Same as you reference below. >I read: > >http://www.linuxdoc.org/HOWTO/DNS-HOWTO-4.html > ><quote> > >In large, well organized, academic or ISP (Internet Service Provider) >networks you will sometimes find that the network people have set up a >forwarder hierarchy of DNS servers which helps lighten the internal >network load and the load on the outside servers as well. It's not >easy to know if you're inside such a network or not. But by using the >DNS server of your network provider as a ``forwarder'' you can make >the responses to queries faster and less of a load on your >network. This works by your nameserver forwarding queries to your ISP >nameserver. Each time this happens you will dip into the big cache of >your ISPs nameserver, thus speeding your queries up, your nameserver >does not have to do all the work itself. If you use a modem this can >be quite a win. For the sake of this example we assume that your >network provider has two name servers they want you to use, with IP >numbers 10.0.0.1 and 10.1.0.1. Then, in your named.conf file, inside >the opening section called ``options'', insert these lines: > ></quote> That's a mixed up description. You have to go to your ISP if you don't know the IP address you're looking for, OR you have to go to some other DNS server. Either way you have to get the traffic from your LAN to the Internet. Using your ISP's nameserver as a forwarder if you have several nameservers yourself is pointless. The point of having a forwarding nameserver is to reduce the amount of traffic over the wire to your ISP. Essentially, if the nameserver you're treating as a forwarder (i.e. your other local namservers go to it first) is on your ISP, then there is no reduction in DNS traffic across the pipe to your ISP, is there? >----------------------------------------------------------------- > >The way I interpret that is that if an address cannot be resolved in >my DNS cache, then it looks to my ISP's nameserver (and ideally finds >the answer in its cache). Otherwise how is this any different than >putting the ISP's nameservers in /etc/resolv.conf (I'm gathering that >you're saying it's not any different). Exactly. It isn't, effectively. The difference with forwarding comes between DNS servers. It simply means that if you have multiple DNS servers in your own institution, A, B, C, D, and E, then A, B, C, and D will go to E before they go out to the Internet independently, which reduces the bandwidth usage of the link to the outside world, which used to be metered (and charged for accordingly). >Here's another site that seems to match my understanding: > >http://www.thelinuxreview.com/howto/ppp/x1531.htm > ><quote> > >You can happily use the domain name servers located at your ISP. You >can also set up a local caching only (secondary) name server that is >brought up by the ip-up script. There is an advantage to running a >local (caching only) name server: it will save you time and bandwidth >(if you frequently contact the same sites during a long online >session). Yes, but this is in contrast to not using a DNS server at all, not in contrast to using multiple non-forwarding servers and a local forwarder. There is no mention of forwarding in that paragraph. >The DNS configuration for a caching only nameserver (that uses a >"forwarders" line in the named.boot file pointing at your ISPs DNS) is >relatively simple. The O'Reilly book (DNS and Bind) explains all >you'll need to know. That's exactly where I got it from! Julian. ======================= ></quote> > >----------------------------------------------------------------- > >Dave > > > >_______________________________________________ >Redhat-list mailing list >[EMAIL PROTECTED] >https://listman.redhat.com/mailman/listinfo/redhat-list ---------------------------------------------------------------- Just because I'm paranoid doesn't mean they aren't after me ... Julian Opificius. ICQ 3268206. ---------------------------------------------------------------- _______________________________________________ Redhat-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/redhat-list
