DNS Flashcards
SOA
Start Of Authority.
Holds info of name servers that are authoritative for a zone. Holds info about how long records are cached (ttL)
DNS Zones
A DNS zone is any distinct, contiguous portion of the domain name space in the Domain Name System (DNS) for which administrative responsibility has been delegated to a single manager. The domain name space of the Internet is organized into a hierarchical layout of subdomains below the DNS root domain.
IDE
Integrated Development Environment
SOA
Start Of Authority
IDE
Integrated Development Environment
SSH
Secure Shell (SSH), sometimes known as Secure Socket Shell, is a UNIX-based command interface and protocol for securely getting access to a remote computer. It is widely used by network administrators to control Web and other kinds of servers remotely. SSH is actually a suite of three utilities - slogin, ssh, and scp - that are secure versions of the earlier UNIX utilities, rlogin, rsh, and rcp. SSH commands are encrypted and secure in several ways. Both ends of the client/server connection are authenticated using a digital certificate, and passwords are protected by being encrypted.
cache.dns
the file that holds the addresses of the root servers
Hostname
www.
FQDN
fully qualified domain name
www.wiredbraincoffe.com
Query
process of asking questions of a dns server to get data were looking for
Caching
process that dns servers use for storing data.
Prevents the internet from crippling under dns queries
DNS root zone
served by 13 root server clusters That are authoritative for the queries for the top level domains of the internet
TLDs
top level domains
.com, .net, etc
root server names
a.root-servers.net through m
DNS hierarchy
root, tld, sub domain, host names
how DNS avoids endless querying
address of at least 1 root server must be loaded into dns via an address file
Sub Domain
the domain names that can be purchased via a registrar or made on your internal NW. e.g. pluralsight.
Host Names
represent the resources were trying to access.
point to websites so they can be accessed via a URL inside your browser. e.g. www. , blog. , etc.
what top level domain is www.pluralsight.com hosted in?
the .com top level domain
the two types of DNS queries
Iterative queries and recursive queries
Iterative queries
performed by dNs servers when they are querying agains a root server.
Provide a referral or the answer.
Recursive queries
Used by DNS clients.
Returns either the answer or an error
events of DNS
- client sends recursive query to the DNS server.
- DNS server doesn’t know so it sends an iterative query to a root name server
- referal to .com name server
- refferal to wiredbraincoffe.com name server which returns the answer
- 1st server is caching the whole time so it won’t have to go through the iterative query process next time
how to test DNS connection
- test internet connection with ping against a public server
- test ping against target DNS server
how to install DNS
install DNS through roles / features in Server Manager of Windows Server
MMC
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Forward lookup zones
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Reverse Lookup Zones
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Conditional Forwarders
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RTO with ping
means pinged site may have blocked people from pinging their website. Not an issue if your not testing NW connectivity
Root Hints
Applies To: Windows Server 2008 R2. You can use root hints to prepare servers that are authoritative for nonroot zones so that they can discover authoritative servers that manage domains at a higher level or in other subtrees of the DNS domain namespace.
Test Ping after DNS installation
ping the FQDN,
make sure it resolved the IP address
Forwarding
the process when a server is set to use an “upstream Server” to resolve DNS queries from clients instead of using the traditional method of using root hints.
Benefits of Forwarding
allows you remove the load of Iterative queries process from your server.
Also allows you to “streamline” Dns query requests in organizations with multiple DNS servers.
Improved security and NW performance
Forwarding Environment Setup
Internal DNS servers, Core DNS server
Core DNS server acts as single point that is actually going out to the internet and doing queries. Internal DNS servers are responsible for going back and forth with Core DNS Server.
Minimizes impact on WAN and improves security
Instead of all servers going outside the NW, queries go to core DNS server(s) that go out to the internet to do queries.
Server Level / Standard Forwarders
Sends all DNS queries for unknown zone records that a server receives to a specified server
Will be used first before Root Hints kicks in. If Forwarder fails then root hints kicks in
Conditional Forwarders
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Zone Records
unknown zone records
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AD
Active Directory
DNS Zone
needed to resolve resources for internal clients. A set of DNS records used to resolve Domain Name Resources related to a Domain. Not the same Domain for AD. Domains for Name Resolution (e.g. pluralsight.com, microsoft.com) and Domains for AD are different
how are zones stored
File based or AD integrated
Primary Zones
they are read-write and File-based. All data is stored in a file on a DNS server only one primary zone per environment on a single server
Secondary Zones
read-only and file-based. Since they are read-only they are good at providing additional DNS for Primary or AD integrated zones. Respond to client request but can’t make changes on them.
Active Directory Integrated Zone
read-write zone. Stored in AD. caveat for ad int. is it needs to be running on a “domain controller” in your AD environments.
Recommended is you are running AD. More secure, easier to centrally manage DNS, ect.
NS Record
Name Server record.
Identifies all servers that hold records for a specific zone.
“A” Record
Host / Address record.
Most often used.
does host name to IPv4 address resolution.
Quad A is for IPv6
An A (address) record is a DNS record that can be used to point your domain name and host names to a static IP address
PTR Record
Pointer Record.
Resolves IP address to host name. basically reverse mapping. Stored in a Reverse Lookup Zone inside DNS.
A PTR record (sometimes called a “host PTR record”) is what lets someone do a “reverse” DNS lookup - that is, they have your IP address and want to know what your host/domain is
CNAMe Record
Alias Record.
Creates and alias or alternate DNS domain name for a specified host name. Allows you to give a secondary name to a resource on your environments.
A CNAME record maps an alias or nickname to the real or Canonical name which may lie outside the current zone. Canonical means expected or real name
SRV Record
Service Locator.
Point to specific services. Used heavily in an AD environment because they allow domain members to find many of the resources that are needed w/in AD
MX Record
Mail Exchanger.
Allow mail servers to id servers that are responsible for handling mail for a remote domain. Allows mail traffic to travel between mail servers.
Record general def.
In computer data processing, a record is a collection of data items arranged for processing by a program. Multiple records are contained in a file or data set. The organization of data in the record is usually prescribed by the programming language that defines the record’s organization and/or by the application that processes it. Typically, records can be of fixed-length or be of variable length with the length information contained within the record.
Forward Lookup Zone
A forward lookup zone is a DNS zone in which hostname to IP address relations are stored. When a computer requests the IP address of a specific hostname, the forward lookup zone is queried and the result is returned.
Zone Definition
In the domain name system (DNS) environment, a zone is the name space allocated for a particular server. A zone file maintains instructions for resolving specified Internet domain names to the appropriate number form of an Internet Protocol address (an IP address).
name space
In general, a namespace is a container for a set of identifiers (also known as symbols, names). Namespaces provide a level of direction to specific identifiers, thus making it possible to distinguish between identifiers with the same exact name. For example, a surname could be thought of as a namespace that makes it possible to distinguish people who have the same given name. In computer programming, namespaces are typically employed for the purpose of grouping symbols and identifiers around a particular functionality.
File Zone
A zone file is a small set of instructions for resolving specified Internet domain names to the appropriate number form of an Internet Protocol address (an IP address). These instructions are ordinarily quite simple and reside in a file on the server that administers a site. Zone files can be used with HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), or SMTP (Simple Mail Transfer Protocol) addresses.
Ideally, a Web zone file should allow resolution of domains either with or without the three letters www. For example, both of these Internet addresses yield the same result:
http: //www.whatis.com
http: //whatis.com
This indicates that the server administrator has written the zone file properly for this Web domain.
Forward DNS Zones
DNS zones contain the records for the mapping of domain names to IP addresses or other information. The resolution of a domain name to its assigned information is also referred to as forward resolution and the DNS zones associated with such processes are often referred to as forward zones.
The term arose as the opposite of reverse zones, which are used for the reverse process: finding the DNS name associated with an IP address. Such reverse zones are maintained in the Internet Address and Routing Parameter Area (domain arpa).
Another common use of the term forward zone refers to a specific configuration of DNS name servers, particularly caching name servers, in which resolution of a domain name is forwarded to another name server that is authoritative for the domain in question, rather than being answered from the established cache memory.
Zone
Each zone stores information about one or more contiguous DNS domains
Reverse Lookup Zone
A reverse lookup zone does just the opposite. When a computer requests the hostname of an IP address, the reverse lookup zone is queried and the result is returned
Forward DNS lookup
Forward DNS lookup is using an Internet domain name to find an IP address. Reverse DNS lookup is using an Internet IP address to find a domain name. When you enter the address for a Web site at your browser (the address is formally called the Uniform Resource Locator, or URL), the address is transmitted to a nearby router which does a forward DNS lookup in a routing table to locate the IP address. Forward DNS (which stands for domain name system) lookup is the more common lookup since most users think in terms of domain names rather than IP addresses. However, occasionally you may see a Web page with a URL in which the domain name part is expressed as an IP address (sometimes called a dot address) and want to be able to see its domain name. An Internet facility that lets you do either forward or reverse DNS lookup yourself is called nslookup. It comes with some operating systems or you can download the program and install it in your computer.
DNS Zone Definition
A SET of DNS RECORDS used to resolve domain name resources related to a
DNS Resource Record
A resource record (RR) is the basic data element in the domain name system.
Domain (Internet Definition)
On the Internet, a domain consists of a set of network addresses. This domain is organized in levels.
Domain (DNS context)
in the Internet’s domain name system (DNS), a domain is a name with which name server records are associated that describe subdomains or host. For example, “whatis.com” could be a domain with records for “www.whatis.com” and “www1.whatis.com,” and so forth.
Resource (Dictionary Definition)
a source of supply, support, or aid, especially one that can be readily drawn upon when needed.
The 3 Zone Types
Primary Zones, Secondary Zones, Active Directory Integrated Zones
Name Server
A name server is a web server that has DNS software installed on it, particularly a server that is managed by a web host that is specifically designated for managing the domain names that are associated with all of the hosting provider’s accounts.
Technically, any web server can have DNS software installed on it, making the server a name server
web hosts
ljnj
What is a zone?
In the domain name system (DNS) environment, a zone is the name space allocated for a particular server. A zone file maintains instructions for resolving specified Internet domain names to the appropriate number form of an Internet Protocol address (an IP address).
