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 subdomains, and then delegating the subdomains to create new zones. A responsible parent also works hard at maintaining the relationship between the name servers authoritative for her zone and its children; she ensures 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 minimal disruption and inconvenience.