Chapter 8, Key Terms

name query

An inverse DNS query that seeks to obtain a domain name for a corresponding numeric address.

nonauthoritative response

Name, address, or RR information fron a DNS server that's not authoritative for the DNS zone being queried (such responses originate from caches on such servers).

name resolution protocols

Procedures that govern the rules and conventions used in manually and dynamically providing for name resolution systems in a networked environment.

inverse DNS query

A DNS query that supplies an IP address for conversion to a corresponding domain name. These DNS qeuries are often used to double-check user identities to make sure that the domain names they present match the IP addresses in their packet headers.

iterative query

A DNS query that targets one specific DNS server and terminates with whatever response may be forthcoming, whether that response is a definite answer, an error message, a null (no information) reply, or a pointer to another name.

Address (A) record

A DNS resource record that maps IPv4 addreses to hosts within a domain.

AAAA record

A DNS resource record that maps Ipv6 addresses to hosts within a domain.

host information (HINFO) record

A DNS resource record that provides information about some specific host, as specified by its domain name.

mail exchange (MX) record

A DNS resource record that's used to identify the domain name for the e-mail server that handles any particular domain or subdomain, or that's used to route email traffic from one e-mail server to another while the e-mail is in transit from sender to receiver.

caching-only server

A DNS server that does not have primary or secondary zone database responsibilities; this type of server is used only to cache already resolved domain names and addresses, as well as related error information.

caching server

A DNS server that stores valid name and address pairs already looked up, along with invalid names and addresses already detected. Any DNS server can cache data, including primary, secondary, and caching-only DNS servers.

address request

A DNS service request for an IP address that matches a domain name.

name resolver

A client-side software component, usually for part of a TCP/IP stack implementation, that's responsible for issuing DNS queries for applications and relaying whatever responses come back to those applications.

Nbstat

A command-line program that returns statistics on NetBIOS, using NetBT if TCP/IP is installed on the machine fron which it is run. This command-line program is a simple tool that displays the state of a particular NetBIOS clients and NetBIOS name resolution in general.

distributed database technology

A database that's managed by multiple database servers, each of which has responsibility for some distinct portion of a global database. As such, DNS is nonpareil in its effective use of d__________ d_______ t_________.

DNS database segment

A distinct and autonomous subset of data from the DNS name and address hierarchy. This subset of data usually corresponds to a DNS database zone and is stored in a collection of interrelated zone files.

DNS round robin

A method of managing server congestion in which a DNS server keeps track of which IP addresses it has provided most recently for a specific translation and rotates them within the pool or list of addresses available. The DNS server can distribute the processing load, thus avoiding server congestion.

ipv6-literal.net name

A name for an IPv6 address used for services on computers that do not recognize IPv6 address syntax. Also referred to as an ipv6 literal.

Peer Name Resolution Protocol (PNRP)

A name resolution protocol used for peer-to-peer network environments and that provides secure and scalable resolution services.

Link-Local Multicast Name Resolution (LLMNR)

A protocol that provides name resolution services on local networks for IPv4 and IPv6 Windows computers.

authoritative response

A reply to a query from the name server thats authoritative for the zone in which the requested name or address resides.

fully qualified domain name (FQDN)

A special form of domain name that ends with a period to indicate the root of the domain name hierarchy. You must use FQDNs in DNS A and PTR resource records.

HOSTS

A special text file that lists known domain names and corresponding IP addresses, thereby defining a static method for domain name resolution. Until DNS was implemented, _____ files provided the sole means for name resolution on the precursor to the Internet, the ARPANET.

negative caching

A technique for storing error messages in a local cache so that repeating a query that previously produced an error message can be satisfied more quickly than if that query was forwarded to some other DNS name server.

IP spoofing

A technique whereby a programmer constructs an IP packet that presents domain name credentials that differ from the IP address in the packet header. This technique is often used in illicit network break-in attempts or to impersonate users or packet origination.

incremental zone transfer

A type of DNS query that limits updates from a primary DNS server to one or more secondary DNS servers only to data that has changed on the primary server.

Nslookup

A widely implemented command-line program that supports DNS lookup and reporting capabilities. Tthe "Ns" in this command name stand for "name server," so it's reasonable to think of this as a general-purpose name server lookup tool.

multihomed

Containing multiple network interfaces capable of attaching to multiple subnets.

caching

Stroring remote information locally, once obtained, so that if it is needed again, it may be accessed much more quickly. Both DNS resolvers (clients) and DNS servers cache DNS data to lower the odds that a remote query will have to be resolved.

canonical name (CNAME) record

The DNS RR used to define database aliases, primarily to make it quicker and easier to edit and manage DNS zone files.

name server (NS) record

The DNS resource record that identifies name servers that are authoritative for some particular domain or subdomain. Often used as a mechanism to delegate authority for DNS subdomains downward on the domain name hierarchy.

pointer (PTR) record

The DNS resource record that's used for inverse lookups to map numeric IP addresses to domain names.

authoritative server

The DNS server thats responsible for one or more particular zones in the DNS database environment.

domain name hierarchy

The entire global namespace for the domain names that DNS manages on the Internet. This space includes all registered and active (and therefore, valid and usable) domain names.

BIND (Berkeley Internet Name Domain)

The most popular implementationof DNS server software on the Internet today (originally introduced as part of BSD UNIX 4.3). Today, there are BIND implementations available for nearly every computing platform including Windows Server 2003 and Windows Server 2008.

primary DNS server

The name server that's authoritative for some particular domain or subdomain and has primary custody over the DNS database segment (and related zone files) for that domain or subdomain.

delegation of authority

The principle whereby one name server designates another name server to handle some or all of the zone files for the domain or subdomains under its purview. The DNS NS resource record provides the pointer mechanism that name servers use to delegate authority.

domain name resolution

The process whereby DNS translates a domain name into a corresponding numeric IP address.