OBJ 1.6 DNS / NTP X Flashcards
A record type
▪ Address Record
▪ Used to link a hostname to an IPv4 address
▪ A records work for IPv4 addresses
AAAA record type
▪ Address Record
▪ AAAA records work for IPv6 addresses
CNAME (canonical name) record type
Used instead of a A record or AAAA record if you want to point a domain to another domain name or subdomain
MX (mail exchange) record type
▪ Used to direct emails to a mail serve
▪ Used to indicate how email messages should be routed using the Simple Mail Transfer Protocol, or SMTP, over port 25
▪ Can only be used to point to another domain, not an IP address
SOA (state of authority) record type
Used to store important information about a domain or zone
PTR (pointer) record type
Used to correlate an IP address with a domain name
The opposite of an A record
Always stored under the .arpa (top-level domain)
TXT (text) record type
▪ The opposite of an A record
▪ Always stored under the .arpa (top-level domain)
SRV (service) record type
▪ Used to specify a host and port for a specific service
▪ Can specify a port along with our IP address
Global hierarchy (Root DNS servers)
The highest level in the DNS hierarchy tree and the root name server answers requests in the root zone
▪ These servers contain the global list of all the top-level domains, such as .com, .net, .org, .mil, and others
Zone transfers
Sharing of information between DNS servers about which domain names they have and their associated IP addresses
DNS resolver
▪ Also known as a DNS cache located on an individual host
▪ This temporary database remembers the answers it received from the DNS server
Recursive lookup/interactive lookup
Recursive- DNS server will hunt it down and report back to your
resolver
Interactive- DNS resolve will continually query DNS servers until it finds the one with the IP for the domain
NTP - stratum/clients
Synchronizes clocks between systems communicating over a packet-switched, variable-latency data network. Can handle a maximum of 15 stratum levels
