Study Guide - DNS Server Test 1

What does DNS stand for?

Domain Name System

DNS zones are populated with resource records via the following records:

Dynamic Updates NIC Registration (static) Manually

hostname

Individual computers exist within a domain. Each computer in the domain must have its own name, referred to as the hostname.

three common types of queries a client can make to a DNS server

Recursive queries Iterative queries Reverse lookup queries

fully qualified domain name (FQDN)

The combination of a hostname, an organizations domain name, and the Internet top-level domain name creates what is called a fully qualified domain name (FQDN) that is unique across the Internet. Hostnames used inside domains are added at the beginning of the domain name and are also referred to by their FQDNs. The maximum length of a FQDN is 255 characters.

DNS servers can remember recently resolved names:

it is important that DNS servers can cache the results of recent name resolutions. Otherwise, name resolution traffic that could result.

Active Directory-integrated zone

stores its data in one or more application directory partitions that are replicated along with other AD DS directory partitions. This helps to ensure that zone data remains up-to-date on all domain controllers hosting DNS in the domain.

iterative query

the queried name server provides the best answer it currently has to the resolver. A DNS server typically performs this type of query to other DNS servers after it has received a recursive query from a resolver.

recursive and iterative queries

try to do the same task in different ways. These are both types of forward lookup queries and are used to resolve a FQDN located somewhere on the Internet to its IP address. They are analogous to locating a phone number for a person whose name you know.

Manually

DNS records can be created manually in the zone by an administrator. These records are static by nature and can be changed only by an administrator. If the hostname or IP address changes on a server, you must update the DNS record to ensure proper name resolution.

purposes of stub zones:

Maintain a current list of delegated zone information within a hierarchy of DNS zones. Provide improved name resolution by enabling a DNS server to rapidly locate the stub zone's list of name servers without the need for querying other servers to locate the appropriate DNS server. Simplify the administration of DNS by enabling the distribution of the list of authoritative DNS servers through out a large enterprise network without the need for hosting a large number of secondary zones.

New Host (A or AAAA) Records

A host resource record maps the FQDN of any computer (host) in the domain to its IP address. Normally the appropriate host record is dynamically added or updated when the host obtains it IP configuration from DHCP. An A resource record is used on an IPv4 network, and an AAAA resource record is used on an IPv6 network;

New Alias (CNAME)

A new alias or canonical name (CNAME) record is an alias for an existing host A or AAAA record in a DNS name. CNAME records are useful if you need to create custom FQDNs or user-friendly names for a specific resource. To create a CNAME record, right-click the DNS zone and select New Alias (CNAME)

reverse lookup query

A reverse lookup query is the opposite- given an IP address, it attempts to locate the FQDN of the host using this address. An analogy would be the locating of an individual or company that is using a known telephone number. A resolver furnishes an IP address to the name server and requests that it be resolved to a hostname. This is the purpose of a reverse lookup query. In reverse lookup, the client sends the IP address to the DNS server and the DNS server replies with the name.

Dynamic Updates

As a DHCP server hands out IP addresses, it registers the client hostname or FQDN and IP address with the DNS server. If the hostname or IP address changes, the DNS record is updated accordingly

zone

Each DNS name server stores information about a discrete portion of the Internet namespace. Such a portion is known as a zone, and the DNS server that is primarily responsible for each zone is considered to be authoritative for that zone. Zones are defined by who looks after maintaining the records that they contain. Each DNS server provides for several types of zones, including primary, secondary, stub, and Active Directory-integrated. You can have forward and reverse lookup zones in each of these zone types.

server properties

Every DNS server has a Properties dialog box that enables you to configure server properties that are applied to all zones hosted by the server. In the DNS Manager console, select DNS server, right-click it, and select Properties to display this dialog box.

NIC Registration (static)

For computers with static IP addresses, the OS attempts to register the connection's address in DNS if the option is enabled under the Advanced TCP/IP Properties of the network adapter. As the connection's address is registered, a static record is added to DNS. If the hostname or IP address changes, it may be reregistered with the command

Using Active Directory integrated-zones also provides the following benefits:

It promotes fault tolerance because data is always available and can always be updated even if one of the servers fails. If a DNS server hosting a primary zone outside of AD DS fails, it is not possible to update its data because no mechanism exists for promoting a secondary DNS server to primary. Each writable domain controller on which DNS is installed as a master server and enables updates to the zones for which they are authoritative; no separate DNS zone transfer topology is needed. Security is enhanced because you can configure dynamic updates to be secured; by contrast, zone data not integrated with AD DS is stored in plaintext files that users can access, modify, or delete.

Top-level Domains

Originally there were eight top-level domains; .arpa, .com, .edu, .gov, .int, .mil, .net. Currently there are over 175 top-level domain names across the Internet.

secondary server

The server that hosts a secondary zone is frequently called the secondary server

master server

The server that hosts the primary zone is frequently called the master server.

Root-level Domains

The top of the hierarchy is called the root domain. The root node uses a null label and is specified by a ".". Connecting the top-level domains, it is not included in domain names.

DNS server software is capable of referring queries to other DNS servers as required.

They resolve local and external queries for machines on your network and referring queries to external networks to the appropriate location.

recursive query

When you type a FQDN into the address field of your browser and press Enter, you are sending a query to the server configured as a preferred DNS server for the IP address of this FQDN. The name server receiving this query must respond with either the IP address for a name or an error stating that data of the requested type doesn't exist or that the domain name specified doesn't exist.

primary zone

a master copy of zone data hosted on a DNS server that is the primary source of information for records found in this zone.

secondary zone

an additional copy of DNS zone data hosted on a DNS server that is a secondary source for this zone information. This server obtains the zone information from the server hosting the corresponding primary zone. Using secondary zones improves name resolution services on the network by providing redundancy and load balancing.

stub zone

contains source information about authoritative name servers for its zone only. The DNS server hosting the stub zone obtains its information from another server that hosts a primary or secondary copy of the same zone data.

second-level domains

newsday.com would be a second-level domain and is actually a subdomain of the .com top-level domain. Second-level domains can be divided into their own subdomains, such as sales.newsday.com. These subdomains can be further subdivided up to a limit of 127 levels. Responsibility of designing, naming, and maintaining these lower-level domains or subdomains, rests with the administrator of the DNS server at the second-level domain.

forward lookup zone

resolves a computer's FQDN to its IP address,

reverse lookup zone

resolves an IP address to the corresponding FQDN.