On Nov 24, 2009, at 12:21 PM, Templin, Fred L wrote: > The way ISATAP is currently specified, it expects to get a > connection-specific DNS suffix from the DHCP server (i.e., > from a domain name option) and then self-constructs an FQDN > by prepending the well-known string "isatap" (e.g., as > "isatap.example.com" when the suffix is "example.com"). The > ISATAP client then resolves the FQDN itself by consulting > the DNS.
That makes sense. You might want to mention it in the draft... :') However, I will reiterate that the DHCP server configuration never changes if you just put FQDNs in the configuration and let the DHCP server resolve them. The ISC server resolves them synchronously and caches them for an hour; the Nominum server resolves them asynchronously and assumes that you have a fast local DNS cache, so it doesn't cache them internally at all. I don't know what other DNS servers do specifically, but my understanding is that thebehavior is similar. So you get the same behavior whether you let the DHCP server resolve the FQDN, or whether you make the ISATAP implementation do it, unless you have really long leases or really short TTLs, neither of which I would expect to be common practice. So by sending FQDNs it seems like you're setting up an unnecessary wrestling match between two styles of doing things; I would argue that for a DHCP-based implementation, you really ought not to do that, if only because sending FQDNs tends to consume more DHCP packet space, which is a scarce resource. _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
