1.8 DHCP/DNS services Flashcards
How does a DHCP reservation work?
When the client requests an IP address by sending a message to the DHCP server, the server will assign an IP from its DHCP scope and reserve it based on its MAC address.
It will match IP addresses to a specified MAC address.
What is a DHCP relay?
It is used to forward/proxy client requests for IP configurations across different physical subnets.
DNS is considered to be a heirarchal system, why?
DNS follows a specific path across a distributed database to locate the record assocaited with your query.
A query gets redirected from a root server to gTLD servers or ccTLD servers based on the URL presented.
What is a FQDN?
Fully Qualified Domain Name; It is a completely specified domain name that includes the top-level domain. Represents a web, mail, or file server.
(www.google.com -> google.com is the FQDN)
What is a URL?
Uniform Resource Locator;
An address that combines domain name and filepath syntax.
Contains the FQDN with method of accessing information.
(Https:// being a method of access.)
What is an internal DNS?
A DNS server maintained by and for exclusive use by an organization for internal devices.
What is an external DNS?
A DNS service provided for the public that does not have internal device information.
What is 3rd party/cloud-hosted DNS? What is its benefit?
DNS services meant to be used internally within an organization, but is maintained by a 3rd party.
They are highly scaleable for large businsesses or organizations that have services around the world.
What is an A record?
Address record;
Name to IP address.
It defines the IPv4 address of a host/FQDN.
What is an AAAA record?
Address record;
Name to IP address.
It defines the IPv6 address of a host/FQDN.
What is a TXT record?
Text;
Does not have to point to other records.
Holds human or machine readible information such as SPF, DKIM, or encryption rules.
What is an SRV record?
Service;
Name to A record.
A newer record that defines how to access a general service, does not need to be specific about the service like MX or CNAME.
Also defines the port number and target device.
For example, can specificy the VoIP controller, SMS server, or Windows domain controller (LDAP).
What is an CNAME record?
Canonical name;
Name to A record or another CNAME record.
Associates aliases (canonical names) with an existing A/AAAA record (primary name).
What is an NS record?
Name Server;
Name to A record.
Specifies the authoratative name server for a domain.
What is an PTR record?
Pointer;
reverse of A/AAAA record. Resolves an IP address into an FQDN.
What is an MX record?
Mail Exchange;
Name to A record.
Determines the domain/host name for an email server.
What is the forward zone?
Forward lookup zones resolve names to IP addresses.
contains A/AAAA records
What is the reverse zone?
Reverse lookup zones resolve IP addresses to names. (contains PTR records).
What is used to comment DNS records?
;
What is used to comment DNS records?
;
What is SPF?
Sender Policy framework;
A TXT record that prevents incoming mail spoofing by checking for authenticity of origin.
What is DKIM?
Domain Keys Identified Mail;
Digitally signs outgoing mail.
Puts public key in DNS record to allow other mail servers to veryfy mail really came from you.
What is DKIM?
Domain Keys Identified Mail;
Digitally signs outgoing mail.
Puts public key in DNS record to allow other mail servers to verify mail really came from you.
What is the most accurate NTP server called when configuring NTP clients?
Stratum 0
What information is needed when configuring NTP?
IP or hostname of NTP server(s), stratum level
What does the DHCP scope define?
Address pool, IP reservations, lease times, subnet masks, default gateway, DNS server, WINS server.
Each subnet should have its own DHCP ___ and ___.
scope and pool.
What is dynamic allocation?
DHCP server gives random IP address each time to a joining device.
What is automatic allocation?
The DHCP server permanently assigns a static IP address to a particular device. The only way to change it is to manually reconfigure the device.
What is static DHCP?
A device will always have the same reserved IP address.
What are the 4 steps of DHCP?
Discover broadcast sent from client
Offer broadcast sent from server
Request broadcast sent from client
Acknowledgement broadcast sent from server
DHCP server uses what port?
UDP/67
What port does a DHCP client use?
UDP/68
What is IPAM?
IP address management;
tools that manage and monitor IP addressing, scope options, DHCP statistics, reservations etc for one or more servers.
