When to Become a Parent
How Many Children?
What to Name Your Children
How to Become a Parent: Creating Subdomains
Subdomains of in-addr.arpa Domains
Managing the Transition to Subdomains
The Life of a Parent
The way Dinah washed her children's faces was this: first she held the poor thing down by its ear with one paw, and then with the other paw she rubbed its face all over, the wrong way, beginning at the nose: and just now, as I said, she was hard at work on the white kitten, which was lying quite still and trying to purr - no doubt feeling that it was all meant for its good.
Once your domain reaches a certain size, or you decide you need to distribute the management of parts of your domain to various entities within your organization, you'll want to divide the domain into subdomains. These subdomains will be the children of your current domain on the domain tree; your domain will be the parent. If you delegate responsibility for your subdomains to another organization, each becomes its own zone, separate from its parent zone. We like to call the management of your subdomains - your children - parenting.
Good parenting starts with carving up your domain sensibly, choosing appropriate names for your child domains, and then delegating the subdomains to create new zones. Responsible parents also work hard at maintaining the relationship between the name servers authoritative for their zone and its children; they ensure that delegation from parent to child is current and correct.
Good parenting is vital to the success of your network, especially as name service becomes critical to navigating between sites. Incorrect delegation to a child zone's name servers can render a site effectively unreachable, while the loss of connectivity to the parent zone's name servers can leave a site unable to reach any hosts outside the local zone.
In this chapter we present our views on when to create subdomains, and we go over how to create and delegate them in some detail. We also discuss management of the parent-child relationship and, finally, how to manage the process of carving up a large domain into smaller subdomains with a minimum of disruption and inconvenience.
Far be it from us to tell you when you should become a parent, but we will be so bold as to offer you some guidelines. You may find some compelling reason to implement subdomains that isn't on our list, but here are some of the most common reasons:
A need to delegate or distribute management of the domain to a number of organizations
The large size of your domain - dividing it would make it easier to manage and offload the name servers for the domain
A need to distinguish hosts' organizational affiliation by including them in particular domains
Once you've decided to have children, the next question to ask yourself is, naturally, how many children to have.