NAK - No Acknowledgement
A none acknowledgement (disapproval) from an authorized point of contact/agent for a domain name record, contact record, or host record that a requested modification should not be completed. When a modification request is received from a source that is not an authorized contact, the request will be rejected and a message will be sent to the listed contacts asking them to ACK (Acknowledge) or NAK (disapprove) the modification.

Name Server
A name server, or domain name server, maintains the cross-reference between domain names and their corresponding IP addresses. Name servers are used so that people don’t have to remember long numerical IP addresses.

Name Server Lookup
One can check which name server their domain is housed by performing a name server lookup. Every ip address is assigned two name servers that will vary depending on where the name is registered.

Name Service
Providing individuals or organizations with domain name-to-Internet Protocol (IP) number resolution by maintaining and making available the hardware, software, and data needed to perform this function. Many Internet Service Providers (ISPs) operate name server and provide their customers with name service when they register a domain name. Most individuals are not in a position to operate a name server on their own and will need to make arrangements for name service with an ISP or some other person or organization.

NIC Fee
This is the fee you pay to your registrar when registering for a domain name.

NIC Handle
When you register a domain with InterNIC, they give you a special ID called a handle. When you register subsequent sites it's a good idea to use the initial NIC handle, or else they'll assign you another one. It only matters when you want to update registration information, it allows you to make changes in one place instead of having to change the registration individually for every domain you have.

Notification
The process of informing individuals and organizations who are listed as authorized points of contact/agent on a domain name record, contact record, or host record that the registry has received a request to modify information in one of the records with which the authorized contacts are associated. All notifications are sent via email to the email addresses that are on file with InterNIC for the authorized points of contact. The notification process provides each authorized point of contact with the opportunity to acknowledge the requested modification with the response "ACK" or to refuse to acknowledge the requested modification, with the response "NAK." Notification is intended to keep all those involved with a domain name or host informed of actions that can affect the operation and functioning of the Host (Name Server).