zone shoud consist of only continous name space
zone name typically is the name of its root domain
in-addr.arpa is a sub-domain, like com, edu, org, etc., for reverse lookup purpose

A zone starts as a storage database for a single DNS domain name. If other domains are added below the domain used to create the zone, these domains can either be part of the same zone or part of another new zone(Delegated away). Delegating means creating a new zone

==== To be continued ====

command line equivalence to MMC's

AD Users and Computers : dsa.msc
AD Sites and Services : dssite.msc
AD domains and Trusts : domain.msc
Services Manager : services.msc
computer management : compmgmt.msc
Schema Manager : schema.msc
DNS Manager: dnsmgmt.msc
Device Manager: devmgmt.msc
Event Viewer: eventvwr
IIS Management: iis.msc (under "inetsrv" folder)
Local Users and Groups Management: lusrmgr.msc

AL, OAL, OAB, and OAB folder under System Folder

Address Lists reside in AD while OAL is put under Exchange system public folder
You can create as many as AL as you wish. The most used AL is GAL, created by Exchange setup by default.

An OAB can contain many OAL's,
An OAL can specify more than one AL's, but a user can download only one of them
A mailbox store is associated with an OAL
Default AL is associated with any newly created mailbox store

Before OAL's can be generated, the address lists, on which OAL based, in Active Directory must be up-to-date. The Exchange SA service calls RUS to maintain AL's. If RUS cannot populate the AL's, Exchange cannot build the OAB's.

once you create a new OAL, you have to wait for public folder store online maintainence to happen overnight to populate messages/attachments into OAB folders

When you delete an OAL, the server dosen't remove the corresponding system folder for 7 days, so if you create a new offline address book with the same name, it is added as OAB version 2 in a subfolder. When this happens, the outlook client can't find the OAB since it is in a folder instead of in System Folder directly.

An OAB server is the server that generates those messages/attachments, it has to be one of the replica server (Q286328)

Default OAL contains data from GAL, but you can populate it with any other ALs. Even you can put more than one ALs into one OAL, but only one AL will be used.

It's often desired to associate different OAL to different mailboxes