5.4. Centralized versus distributed management

This section applies to those organizations that have multiple system administration groups, each responsible for different departments within the organizations. If your organization has centralized remote control of all soft administration, then these issues will be of less interest to you.[8]

[8]Soft administration includes everything that does not require onsite personnel. An example of something that is not soft administration would be replacing a disk drive.

NIS lends itself to allowing you to give system administration groups for a given department within your organization responsibility for maintaining the department's NIS maps without the need for centralized control. However, the nature of hostnames, host addresses, and domain name management is that some central controls or rules are necessary in order to prevent mistakes in one department from affecting other departments and beyond.

There are at least three basic approaches to consider for managing hosts and domains.

Complete centralization

In this model, if someone wants an IP address, he or she contacts a single central committee to get one; the chances of errors are as low as possible, but the latency in getting requests honored is the longest. Adding new subdomains is also centralized. In this model, as there are specific system management groups managing the non-hosts NIS maps for a given department, it is not practical to manage hosts via NIS; you would use DNS exclusively.

Federation

In this model, the central committee has delegated responsibility for portions of the IP address space to individual groups responsible for a DNS subdomain. In this model, either a DNS or a hybrid NIS/DNS model for managing hosts works (such as via the technical rules listed in Section 5.3, "Fully qualified and unqualified hostnames" earlier in this chapter). If the individual groups are using DNS to the exclusion of the NIS hosts map, then there is little work for the central committee other than to maintain the mapping of subdomains to subdomain name servers. The central committee, of course, is responsible for adding or deleting subdomains. If the individual groups use NIS for local hostname information, then the central committee would maintain the entire DNS infrastructure by periodically gathering host map information from each group. This could be done automatically.

Complete decentralization

Each system administration group has the autonomy to modify its NIS host maps as well as the authority to modify the common DNS database. Such a system will not scale as the number of subdomains and system administration groups rises. With too many authorized players, it will be hard to track down problems caused by mistakes, not to mention avoiding duplicate efforts.

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