Single-label DNS name resolution
Single-label domains are missing a top-level domain (TLD) and the normal dot (.) notation associated with domain names. For example, a normal domain is adventure-works.com, whereas a single-label domain is adventure-works.
You find single-label names on networks with legacy Windows Internet Name Service (WINS) deployments. However, as WINS is retired, administrators must plan for providing name resolution for older, legacy WINS-based applications and important resources. Windows has a GlobalNames Zone (GNZ) that can be used to provide name resolution for singlelabel names. GNZ can be deployed in a single forest or across multiple forests to provide static name resolution.
GNZ helps in the transition from WINS to the multi-label standard DNS zones and can therefore be part of a planning strategy for name resolution. You should understand how GNZ varies from domain suffixes and how it has improved performance over multiple domain suffixes in single-label resolution scenarios with several domains. Windows Server 2012 looks first in the GNZ when a single-label resolution query is received. If a record is in the GNZ, it can’t participate in dynamic updates, and dynamic update requests for that record will be refused.

Zone hierarchy and zone delegation
The zone hierarchy is the tree-like structure of DNS, in which the root of the zone is represented by a single dot (.). Up the tree from that root are top-level domains (TLDs) such as .com, .net, and .org. The tree branches out into the private domains that you recognize, like microsoft.com and adventure-works.com.
Zone delegation refers to the ability to respond to queries authoritatively by using a portion of a zone. For example, in the hierarchical nature of DNS, the root servers are responsible for the root of the zone and delegate authority for TLDs to TLD servers who then delegate responsibility for domains such as adventure-works.com to private corporate nameservers.
When a query arrives for www.adventure-works.com, the query begins at the root server, which refers the query to the responsible server for the .com TLD, which then refers to the responsible server for the domain being queried.
In much the same way that root servers delegate to TLD servers, which then delegate to corporate nameservers, you can also delegate portions of corporate domains such as adventure-works.com to other nameservers so that they become authoritative for that part of the zone. For example, you may want to create an authoritative zone for corp.adventure-works.com so that queries are sent to a different server for hosts in that domain.
Zone delegation is configured in the DNS Manager by right-clicking the zone to be delegated and then selecting New Delegation. Doing so invokes the New Zone Delegation Wizard so that the portion of the zone, such as the corp subdomain in the corp.adventure-works.com scenario, can be delegated.