On Fri, 21 Feb 2003 Mark.Andrews@isc.org wrote: > > > On Fri, 21 Feb 2003 Mark.Andrews@isc.org wrote: > > > > > > You haven't shown any proof of that. The "proof" you showed, was the > > > > result of a misconfiguration. > > > > > > No. It is the result of operational reality. Whenever you > > > have a parent and child zones under different administrative > > > controls it is impossible to change both zones simultaniously. > > > It is also impossible using AXFR or any other mechanism > > > which transfers *individual* zones to transfer them to a > > > secondary and guarantee that they will arrive simultaniously. > > > > > > Having parent and child zone under different administrative control > > > is the norm not the execption. > > > > Actually, a parent always has some control over the child. It exercises > > this control through the glue records. When the glue records are in the > > child zone, they need to be merged. > > Which is it. Does the parent control the contents of its zone > or does the child? You seem not to understand the subtlety of the issue. The parent (like real parents) ultimately controls the child, but the child (like real children) has limited autonomy. > > If a zone transfer happens while they > > are inconsistent, it is possible for some strange results to happen. > > Ordinarilly, zone transfers don't happen when they are inconsistent, since > > the inconsistency is usually short. > > It doesn't matter if they normally happen while they are > consistant. You have to get correct behaviour while they > are inconsistant. Changing zone content on SECONDARY servers > is not correct behaviour. Sure it is. Unless you can arrange to conduct both updates simultaneosly. While it would be possible to coordinate such changes on the phone, relativity could come into play someday. It has nothing to do with zone transfers. Its part of the state of the system. Zone transfers is only one way to learn about the state of the system. > > Any zone transfers made during the inconsistent window are corrected so > > long as the child zone is updated with correct information after the > > parent is updated. > > This is a incorrect statement. Could you elaborate? > > Frequently the parent and child zone are under different administrative > > control, and are frequently on different servers. In such a case, the > > contents of the parent zone aren't merged with the child in the child's > > server, and no evidence of the inconsistency is seen through zone > > transfers. However, the inconsistency still exists and may still be > > visible by resolvers and nameservers that lookup the glue records. > > Nobody is claiming that inconsistancies don't occur all the > time. What we are claiming is that those inconsistancies > need to be preserved in SECONDARY servers for the correct > operation of the DNS. That they can only be corrected by > modifying the PRIMARY source of the zones. ??? I can't parse this with respect to your previous statements. Could you rephrase it? During the period in which the zone is inconsistent, there is no guarantee the zone will work. Depending on the nature of the change, wrong information may be given in queries as well. Suppose the parent is removing control from the child, and has updated the glue to remove referals to the child nameservers. For some time (the TTL, at least), the original child servers will be queried. On the other hand, the child zone may not even exist yet on the childs nameservers. Referals to the zone fail. To make a concrete example, Osama registers alquaeda.com, and begins coordinating his evil deeds. The registrar delegates the alquaeda.com as a child of .com. Eventually, the government intervenes, and .com replaces Osamas nameserver glue with new glue pointing to government servers. For a time, this zone will be inconsistent. Note that in this case, the zone transfers will not indicate the inconsistency. However, for a short time, Osama will be able to put up a message warning his followers not to go to the government run site. This can't be avoided, no matter what gyrations you put AXFR through. It makes no difference that the inconsistency _could_, _in_some_cases_, be seen at the secondaries. > > You have obtained no benefits by these constraints. > > There are clear benefits in preserving zone contents on > SECONDARY servers. Such as? Your term "preserving zone contents" is misleading. The zone contents are not corrupted. The glue is inconsistent. What is the benefit of preventing any trace of inconsistency in the secondary? It has nothing to do with IXFR. It has nothing to do with anything. > > It is necessary, since the parent has glue records in the child zone. > > The parent therefore has (always) a part of the child zone. If that server > > also loads the child zone (or perhaps generates part of it dynamically), > > it quite reasonable to merge the records as though the zone includes > > multiple files, which in theory, it does. > > No it isn't. Changes need to come from the PRIMARY source not > from intermediate sources. The intermediate sources aren't making changes. They are, at worst, propogating old information mixed with new information. However, this is visible in other ways besides zone transfers. > > The child zone contents will only be correct when the administrators of > > both zones agree on the contents of the glue records, and update their > > parts of the child zone accordingly. It will not be correct until then, > > regardless of how many zone transfers take place. > > Which is what I've been saying all along. It doesn't require > a server to "correct" the content at a intermediate point. Such > "corrections" actually cause problems. Good. Then you agree that Bind 8 behavior is correct. > > > Nothing in RFC 1033 / 1034 / 1035 says that a server is permitted > > > to alter the content of a zone. The responability for maintaining > > > consistancy between zones is a administrative function. > > > > This is a loaded statement. The part of the server NOT involved in > > responding to queries and zone transfers is part of the administrative > > function. So, as part of that administrative function, it has to be able > > to modify the RR and zones accordingly. Your proposed changes exclude a > > huge part of the potential for intelligence in name servers. And do so > > with no benefits. > > The benefits are correct operation of the DNS regardless of the > propogation timings involved. If servers don't modify slave zone > content then which the master servers are brought into sync all > the servers will be brought into sync. We already have correct operation of DNS. The zone contents are inconsistent until both adminstrators come to agreement. The child zone should be updated last. After the child zone is brought into agreement with the parent glue, zone transfers will be made which are correct. Only then will zone transfers will be correct. Zone transfers made while the administrators are not in agreement will not be correct, even if there is no apparent evidence in the zone data from the child (such as a mixture of new and old glue) they are still incorrect. NS Queries against the parent and child servers will return different results. > This is not guarenteed if the zone content is modified by a > secondary server. > > > > > > > Strange, that was my reaction, too. I'm just trying to be polite. 77 > > % > > > > > > work just fine. We don't want to break 77% of the servers out there. > > > > > > > > > > You really think that it will break those servers? LOL. > > > > > > > > They will not be compliant, and thus will need to be changed. Thus, they > > > > would be broken by definition of not being compliant. > > > > > > So. Just because they will not be compliant doesn't mean > > > that that they need to be replaced immediately. That > > > non-compliance doesn't hurt most of them. For those where > > > it does have a negative impact it will mean that they should > > > be able to request a fix from their vendor. > > > > You seem to make a case that in general, non-compliance doesn't hurt > > anything. This is false, for both technical and commercial reasons. > > Technically, it hurts interoperability, which has some many obvious harms > > I won't go into them. Commercially, implementations make and advertise > > compatibility and standards compliance claims. This retroactively makes > > those claims false, which harms the business and reputation of those other > > vendors. > > They will be harmed much more if they don't correct a common > error now that it has been pointed out. Except, there are no errors, beyond a window of inconsistency that cannot be avoided, and in fact, that window isn't fixed. Nor do you fix the "error". They are _still_ inconsistent for a period. And the child will _still_ have to be updated last. > The claims were made in good faith and will be accepted as > such. I'm not convinced. If they were, we would have argued this before Bind 9 was released, and before a book was sent out. Probably about 3 years ago. Someone knew years ago when they wrote the "backward compatibility" mode, that they had a protocol issue that would have to come before namedroppers. That they delayed for so long doesn't indicate good faith to me. > > 77% will need a fix from the vendor, if we were to accept these changes. > > > > The vendor that made false claims of compatibility and standards > > compliance is Bind 9. It should suffer the commercial damage to its > > business and reputation, as a result. > > BIND 9 conforms to RFC 1034. Nothing in RFC 1034 says to > merge zone content. If fact 1034 says that this a administrative > responsability. It does right now, due to a knowingly reckless exploitation of ambiguity in the AXFR. Once AXFR is clarified, Bind 9 will have to use its 'backward compatibility' mode to be compliant. It is "knowingly reckless" because the Bind 9 implementers _KNEW_ they needed to provide a "backward compatibility". That means they knew what they were doing was incompatible with any (all actually) reasonable interpretation (however ambiguous) of 1034. > > > > Your failure to comprehend the consequences of the changes does not lesse > > n > > > > the effect. We now agree that these changes aren't necessary to support > > > > IXFR. You were part of the bad engineering that led to the unnecessary > > > > creation of these changes in Bind 9. You were also part of the bad > > > > decision making that led to the distribution of these changes to Bind 9 > > > > users prior to standardization, and quite possibly you were part of the > > > > bad decision making that resulted in publishing a book on the subject, > > > > prior to acceptance of your modifications to standards. In short, you hav > > e > > > > shown bad judgement. > > > > > > I never said that they we not necessary for IXFR. I said that > > > that your descripition of how to generate the differences was > > > irrelevent to this discussion. > > > > Ok, you are half way there. They are irrelevant because IXFR is > > irrelevant. These changes are not necessary to IXFR, as I explained that > > IXFR can work with the current AXFR, or even without AXFR. > > IXFR cannot work through SECONDARY servers that change zone > content regardless of whether the content was learnt via > AXFR or IXFR. Sure it can. It doesn't need AXFR at all. And the secondary's aren't making arbitrary changes at all. > > > It was bad engineering to merge the data sets together in the > > > first place. It was not required by RFC 1033/ 1034 / 1035. > > > It had negative consequences. It was good engineering to > > > correct this. It was also good engineering to report a > > > common error to the community so that other vendors could > > > fix their mistakes. > > > > Actually, since the parent has the glue in the child zone, it has part of > > the child zone as well as the master zone. Merging them together is not > > prohibited, and in the case where child and parent have the same > > adminstrator, as might be the case where most of the child is simply > > automatically generated by the nameserver, can make things much easier. > > > > Your constraints preclude this unnecessarilly. > > The constraint in on the SECONDARY server. So? It is still unnecesary. > > Since I can think of cases where it is useful to merge records together, > > it is bad engineering to remove that flexibility and obtain no benefits in > > return. > > > > > > Trying to "belittle" the effects with the "LOL", as opposed to offering > > > > anything substantive, simply suggests that you have no appreciation of th > > e > > > > seriousness of the changes. Perhaps you should take this more seriously. > > > > > > I'm quite aware of what the change requires. I'm also aware > > > that most of the nameserver are used in situations where > > > the zone contents is already preserved because they are not > > > serving zones with parent / child relationships. > > > > Apparently, you aren't even aware that your changes will make all non-bind > > 9 servers non-compliant. Had you been aware of that, it seems you would > > have brought this proposal forward something like 3 years ago, before > > releasing Bind 9, and before publishing a book on the subject. > > Well you obviously have not been reading. ISC is not the > only vendor to come to the same conclusion about preserving > zone content. I suspect that they are just bored with > arguing with you and Dan. I think they just haven't really read the proposal's, and have taken some misleading assurances at face value. > > > Anyone saying that all the nameservers need to be replaced > > > immediately is spreading FUD. LOL the the correct reponse > > > to FUD. > > > > Making 77% of the servers non-compliant is a fact of your proposed > > changes. It is another fact, as explained, that non-compliant servers > > will need to be replaced. Will they suddenly stop working? It depends on > > whether other implementations want to implement a "backwards > > compatibility" mode. If they don't implement this mode, then the answer is > > yes, they will stop working as soon as these updates are deployed by other > > vendors. Of course, this is a bad result. > > Well they havn't stopped working in the last two years that > this code has been out there. Nothing in this drafts stops > a server implementing it taking to any other server. Uhh, wrong. The drafts make the current AXFR non-compliant. There is nothing that would require a server to implement the old AXFR and provide a "backwards compatibility" mode such as Bind 9 has. So servers running today, won't be able to talk to strictly compliant servers that don't have a backwards compatibility mode. > There is one backwards compatiblity switch which is only > requires if you decide to send multiple records in a single > messages. A server is not required to send multiple records > in a single message. But is allowed to, and a server that can't receive such messages won't be able to get the zone. > > > > 1) It doesn't say that it adds a completely new, incompatible zone > > > > transfer protocol. New protocols should be made through a different > > > > process, which includes experimentation. I'm not against experimenting > > > > with a new protocol. Indeed, I think this idea has some merit. However, i > > t > > > > can't be "end-run standardized" by a "clarification". There is a process. > > > > > > It isn't new. All it is saying is that the contents tramitted > > > out MUST be that transmitted in. This occurs most of the time > > > already. Note BIND is not the only implementation that does > > > this. We have already had reports of 3 other implementations > > > doing this. Even the implementations that don't guarentee the > > > contents do this most of the time. It has no negative effects. > > > > No, Section 3.1 is a whole new derivative of AXFR. That is new. > > Actually it's always been allowed by RFC 1034. Just because > it wasn't implement initially doesn't mean that it was not > allowed. Uhh, wrong, except in an unreasonably broad technical exception due to the vagueness of 1034. > > > > 4) It doesn't say that it changes the definition of zone data to be > > > > public. Zone data is absolutely not "public by definition". It could very > > > > well be useful to tag certain RRs as non-public, and exclude them from > > > > zone transfers to public servers. This "clarification" precludes that. > > > > This is really 2 changes. > > > > > > Nowhere in RFC 1033 / 1034 / 1035 does it say that zone transfers > > > are restricted to secondaries. Nowhere in RFC 1033 / 1034 / 1035 > > > does it say that you should restrict zone tranfers. > > > > I don't think you understood my statement. I'm talking about the > > definition of zone data. Nowhere does 1034 etc say that zone data is > > public. It may well have been thought to be public, originally, but since > > I can easily see a useful purpose in withholding some private RRs, there > > isn't any reason to preclude that behavior. > > Does this address your concerns? No. Because it might be reasonable not to give complete zone data. > "The zone transfer protocol allows read-only access to the complete > zone data. When the data being served to the public it is > generally acceptable to allow unrestricted access to it via AXFR. > Sites that wish to avoid disclosing their full zone data MAY > restrict zone transfer access to authorized slaves." > > If you have part of a zone to which you would normally > return REFUSED to I suggest that you also return REFUSED > to AXFR. > > If you want to be able to return partial zones then I suggest > that a new TYPE be defined so that receipients can know > that the results will be incomplete. So far as the secondary is concerned, the zone is complete. If you do this, you don't want to tell people that you have some data that isn't public. Nor would you ever need to.
