I hadn't read this thread until just a few minutes ago. (Last week was really busy.) :-)
But at least for OL2003 RTM, the complete process goes like this: 1) If "DS Server" registry key set, use that GC 2) If "Closest GC" registry key set, call UseDsGetDcName() 3) If fast network adapter, get DS Referral from home Exchange server 4) If slow network adapter, attempt connect with GC in MAPI profile 5) Connect to DSProxy from home Exchange server As was pointed out before, the process varies between versions of Outlook (and even service packs). But, to the best of my knowledge, Outlook has never been DNS aware (insofar as finding DC/GCs). All that being said, I'm a BIG believer in using cached mode with OL2003, in terms of improving the user experience, except when the OAB is really large and changes often cause the full OAB to be d/l'ed. Even then, there are registry changes that can make it "OK". -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of joe Sent: Sunday, August 01, 2004 8:37 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] outlook / gc client discovery Excellent, further proof. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael B. Smith Sent: Sunday, August 01, 2004 8:08 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] outlook / gc client discovery It gets the closest DC by using UseDsGetDcName(). -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of joe Sent: Sunday, August 01, 2004 6:34 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] outlook / gc client discovery Barring a network trace disproving it I would agree. Setting the outlook client to use closest *should* fall back and use what the client considers closest, going to the Exchange server and asking at that point would be silly and I don't actually believe Exchange has that functionality. joe -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ken Cornetet Sent: Monday, July 26, 2004 12:57 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] outlook / gc client discovery Hmmm, I never really thought about how Outlook decides what's the "closest" GC. I'm going to make a complete WAG and say that DSPROXY is not used, and outlook does a DNS lookup for GCs relying on IP subnet sorting to get the "closest". -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Graham Turner Sent: Saturday, July 24, 2004 12:14 PM To: [EMAIL PROTECTED] Subject: Re: [ActiveDir] outlook / gc client discovery Ken, thanks for the post reply on this one. Was wondering further if you had any information on this relating to the actual mechanics of this. My understanding has been that OL 2002 has no concept of site awareness given this what i am struggling to understand is how the OL2000 'advertises' it site membership given this registry change. seems there are a number of possibilities here - - is the clients interaction with DSPROXY modified ? or - the interaction with DSproxy is actually 'disabled' and OL falls back somehow to a client based DNS lookup ?? TIA GT ----- Original Message ----- From: "Ken Cornetet" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, July 23, 2004 8:34 PM Subject: RE: [ActiveDir] outlook / gc client discovery Outlook 2002 http://support.microsoft.com/default.aspx?scid=kb;en-us;319206&Product=o l2002 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Graham Turner Sent: Friday, July 23, 2004 1:33 PM To: [EMAIL PROTECTED] Subject: Re: [ActiveDir] outlook / gc client discovery Dear all, thanks all for your positive views on this issue. first up i apologise for not chiming in the last week - been away at customer site ! - esp given it was me that opened up the item. my further research into this seems to indicate that GC discovery process seems to vary across versions of Outlook - and specfically Outlook 2003 seems to introduce new processes ?? Would Ken be happy to confirm his version of Outlook - and required reg mods to support local GC discovery with centralised Exchange servers ? - I think i have referenced the "closestGC" reg value but am not sure if this is it TIA GT ----- Original Message ----- From: "Mulnick, Al" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, July 19, 2004 8:25 PM Subject: RE: [ActiveDir] outlook / gc client discovery > Ken, that is a great response. Thanks for taking the time. > > I can see your logic now. :) > > Al > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Ken Cornetet > Sent: Monday, July 19, 2004 3:16 PM > To: [EMAIL PROTECTED] > Subject: RE: [ActiveDir] outlook / gc client discovery > > Well, as you (and Joe) pointed out, a WAN link slow enough to give a > bad user experience with name resolution will also yield poor message > performance. > > Obviously, the best solution is to put an Exchange server at the > location. Unfortunately, many of our smaller locations are simply > unwilling to foot the bill for an Exchange server (and associated > trappings). > > So, we are left with the task of making things better for the users without > spending money. The only thing we can do for free is to make their DC > a GC. > This speeds up name resolution. We can't speed up messaging > performance, so > we simply coach the effected users to not send large attachments, and > tell others to not send them large attachments. We also show users how > to use Outlook in off-line mode. We were hoping that > OL2003's cached mode would help, but it seems to add as many problems > as it > fixes (more experimentation is in the works...). > > Like most other things, it is a trade-off. Our AD is fairly static - > just adding/deleting users here and there, group membership changed > now and again. We looked at the GC replication traffic, and decided > that it didn't look like a problem. > > This seems to work well for us, but obviously everyone's mileage may > vary. I > can easily see how GC replication would be a problem for large > organizations' WANs. > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mulnick, Al > Sent: Monday, July 19, 2004 1:44 PM > To: [EMAIL PROTECTED] > Subject: RE: [ActiveDir] outlook / gc client discovery > > > Aside from cached mode, I think it's valuable to ask this: Is it ok > then to > have the user experience bad performance when it comes to message > content as > long as GAL resolution is good??? > > The point I was trying to get across is that if the link is good > enough to host the Exchange data, it follows that it's also good > enough to host the GAL resolution. The thinking being that the > resolution of names takes far fewer packets to traverse the wire than > it does to open a message body. Obviously there are exceptions when it > comes to user experience, and as Tony > says, cached mode might be an option to "shield" > the user from noticing the crappy latency issues. But cached mode > aside, I > would expect user experience to suck overall if the GAL functions were > bad enough for the user to notice. The only difference across that > link is the > host they talk to assuming no DSProxy in play. > > I'd be interested to hear about the experience and how you solved it, > Ken, as I've never seen it go that way with regularity. I have seen > the odd time > when your situation was true, but it turned out to be a slow GC anyway > and that experience was much less dangerous than the Active Directory > latency issues Joe pointed out. Slow data is always better than > inaccurate data IMHO. > > Al > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Tony Murray > Sent: Monday, July 19, 2004 10:50 AM > To: [EMAIL PROTECTED] > Subject: RE: [ActiveDir] outlook / gc client discovery > > This is where Outlook 2003 in cached mode helps. By default it will always > use the OAB. > > Tony > ---------- Original Message ---------------------------------- > From: "Ken Cornetet" <[EMAIL PROTECTED]> > Reply-To: [EMAIL PROTECTED] > Date: Mon, 19 Jul 2004 09:41:11 -0500 > > Ouch, I hate to disagree with Joe, but we've "been there, done that". > While it's true that the GC traffic volume pales in comparison to the > Exchange traffic, the important metric here is not the bandwidth > usage, but > rather the end user experience. Your users will notice very pokey name > resolution and GAL lookups if they are hitting a GC across a WAN. A T1 > isn't bad, but a 128K link with moderately bad latency is absolutely > painful! > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of joe > Sent: Friday, July 16, 2004 4:43 PM > To: [EMAIL PROTECTED] > Subject: RE: [ActiveDir] outlook / gc client discovery > > > I like to put this most simply as.... > > Use the GCs for the clients that the Exchange Servers are using. If > you have > an Exchange Server in your local site using a local GC, use that GC, > would be silly to go across the WAN. However if your Exchange Server > is across the > WAN, use the GC across the WAN as well. Comparatively the traffic is nothing > compared to Exchange AND you are less likely to be bitten by the > "loosely consistent" nature of Active Directory. > > joe > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mulnick, Al > Sent: Wednesday, July 14, 2004 2:46 PM > To: '[EMAIL PROTECTED]' > Subject: RE: [ActiveDir] outlook / gc client discovery > > Sponsorship? I have no idea what you mean <g> > > "point taken about the size of the address book being small compared > to but > my mind has been that we have servers there with the required > directory information, we might as well use them ???" > > Just because you can, doesn't mean you should. They are two totally > different concepts to say the least. The address book lookups is typically > very small. Although I currently enjoy large network links, that has > not been the norm during my career. I've made similar recommendations > when using 9.6 Kbps links, although that would arguably be a case for considering > putting in a local Exchange server else use avian packet carrier or > cached mode to at least give the illusion of usable performance. > Generally speaking, wherever you put a site, you may also want to > consider putting an Exchange server and GC's. They're not that > different. If you instead decide to put the Exchange mailstores, > where all the user data is located, in a central location, then why > would it make sense to put the GC in a decentralized location? It's a > nice to have, but it's not a requirement in most situations. It > becomes more of a requirement depending > on the links, but if you need to rely on it, you either have a > geographically dispersed network and want more finite control over > user traffic patterns (i.e. don't want the french mailbox users to > have to use the south american GC for address book lookups)else you > have a penchant for > zeroing in on unimportant things. I'll assume the previous in your > case because that would make a lot more sense. > > Bottom line is that there is no reason you wouldn't want to create a > 5.5 > - like topology if centralizing. You would create an active directory site, > put in as many GC's as you needed for Exchange servers/users, and for > each of those machines you'd hardcode the GC's DSProxy can hand out. > Or maybe even create your own Exchange domain without users or your > own domain forest depending on requirements. But to spend the time to > reduce the smallest amount of traffic seems counterproductive to me > except in situations noted above. > > My thoughts anyway. > > Al > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Graham Turner > Sent: Wednesday, July 14, 2004 1:04 PM > To: [EMAIL PROTECTED] > Subject: Re: [ActiveDir] outlook / gc client discovery > > thanks both for post replies - helpful in the extreme > > i do sense that the issue of GC and by implication dlist etc retrieval over > a WAN connection is not regarded as such as a major issue - can only assume > that you have the luxury of very well connected sites ?? > > point taken about the size of the address book being small compared to > but my mind has been that we have servers there with the required > directory information, we might as well use them ??? > > i take point about risk about client not being "intelligent" in its > choice of GC with respect to domainprep etc - suppose this is where > Dsaccess has a > bit more intelligence than the client based discovery process - which > it seems we are not sure about > > will be doing some capturing of the startup of outlook clients so hopefully > something will stick out here > > thanks again for your help > > i always wonder about the sponsorship owed by microsoft to this > mailing list > ?? > > GT > > - > ----- Original Message ----- > From: "Mulnick, Al" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Monday, July 12, 2004 5:36 PM > Subject: RE: [ActiveDir] outlook / gc client discovery > > > > Graham, that's a fairly common question actually, although usually > > in the Exchange groups. It still could be considered on topic here > > for part of that data. > > > > FWIW, it's the dsproxy process that hands out GC's to clients to > > use. > That's > > because of the legacy restrictions the client brings to the equation > > (see: > > > http://www.microsoft.com/technet/prodtechnol/exchange/2000/deploy/upgr > ad > emig > > rate/series/planningguide/p_08_tt1.mspx and search for DSProxy)Note > > that different versions of Outlook will respond differently to this > > process > after > > the first contact is made an a GC is found. DSProxy picks it's GC's > > based on a number of criteria such as whether or not the domain it's > > talking to > is > > domainprepped, how close to the Exchange machine the GC is > > (network), etc. > > > > > > In multi-domain environments, it's not always a good idea to use the > > closestGC method (see: > > http://support.microsoft.com/default.aspx?scid=kb;en-us;Q319206). > > Rather, using a pre-defined becomes more usable as long as that GC > > remains operational and up to date. Since that's against what > > Active Directory > can > > do (multi-master concept) then it becomes a burden that many will > > gripe about (and rightfully so on that one). For those situations, > > recreating Exchange 5.5 with Exchange 2003/Active Directory seems to > > be the best > > workaround: i.e. creating a set of GC's specifically for Exchange > usage. > > This has the added benefit of dedicating GC's to Exchange (better > > performance) and putting it under Exchange operational control > > (environmentally isolated). Some would call that a detriment others > > a > great > > step forward, but all can agree it's just about a waste of hardware > > :) > > > > The problem is that the client doesn't send any site-awareness > information. > > Since Exchange 2003 can't take us back in time while still having to > support > > legacy clients (else many wouldn't buy the upgrade right?), you need > > to > work > > with it to your environmental strengths IMHO. > > > > Why does it only maintain 10 of each? How many does it need? If 10 > aren't > > available, don't you have bigger problems to worry about? The q > > article discusses your second question and gives details about the > > behavior. Like > I > > said, be careful to note the versions and if you're spread out over > > many sites with a centralized Exchange server, consider the > > recreation > > > of Exchange 5.5 functionality with regards to directory service. > > > > Al > > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Graham > > Turner > > Sent: Monday, July 12, 2004 8:10 AM > > To: [EMAIL PROTECTED] > > Subject: [ActiveDir] outlook / gc client discovery > > > > dear all, am a bit nervous posting this on account of going way OT > > as this post falls quite definitely under Outlook 2002 > > configuration, but > > > there is obviously relation to AD so here goes ... > > > > understanding the mechanisms of GC 'discovery' would it seem be very > > important to optimal deployment of outlook / exchange especially in > > remote office scenarios. > > > > the default outlook configuration seems to use the "view" of the AD > topology > > in terms of DC's and GC's as is learnt by DSACCESS - and reads this > > from > the > > server on which the outlook client is homed > > > > qu 1. why does it only maintain 10 of each ??? - this is a bit like > > that > odd > > limitation of 25 DC addresses in the WINS (1C) record - and which 10 > > does > it > > learn ??? > > > > qu 2 seems we can override this default behaviour with a registry > > value (closest GC) - does this reconfigure outlook to behave like > > the logon > server > > discovery process and use native DNS lookups ??? > > > > hope the mail list can be of help on this one > > > > GT List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
