Chapter 3 Flashcards
A (Address) record
A type of DNS data record that maps the IPv4 address of an Internet-connected device to its domain name.
AAAA (Address) record
A type of DNS data record that maps the IPv6 address of an Internet-connected device to its domain name. Pronounced “quad-A record.”
address translation
A technique in which IP addresses used on a private network are assigned a public IP address by a gateway when accessing a public network.
anycast address
A type of IPv6 address that represents a group of interfaces, any one of which (and usually the first available of which) can accept a transmission. At this time, anycast addresses are not designed to be assigned to hosts, such as servers or workstations, but rather to routers.
APIPA (Automatic Private IP Addressing)
A service available on Windows computers that automatically assigns the computer’s NIC a link-local IPv4 address in the range of 169.254.0.1 through 169.254.255.254.
authoritative server
The authority on computer names and their IP addresses for computers in their domains.
broadcast
A message that is read by every node on a network.
broadcast domain
Logically grouped network nodes that can communicate directly via broadcast transmissions. By default, switches and repeating devices, such as hubs, extend broadcast domains. Routers and other Layer 3 devices separate broadcast domains.
caching DNS server
A server that accesses public DNS data and caches the DNS information it collects.
canonical name
The true name of a server, such as www.example.com, as opposed to one of many alias names a server might have, such as ns1.example.com.
classful addressing
An IP addressing convention that adheres to network class distinctions, in which the first 8 bits of a Class A address, the first 16 bits of a Class B address, and the first 24 bits of a Class C address are used for network information.
CLI (command-line interface)
A graphic-free user interface, such as the Command Prompt application in Windows, where technicians can enter commands more quickly and with more flexibility than in a GUI (graphical user interface) environment.
CNAME (Canonical Name) record
A type of DNS data record that holds alternative names for a host.
default gateway
The gateway device that nodes on the network turn to first for access to the outside world.
device ID
See extension identifier.
DHCP (Dynamic Host Configuration Protocol)
An Application layer protocol in the TCP/IP suite that manages the dynamic distribution of IP addresses on a network.
DHCP pool
The predefined range of addresses that can be leased to any network device on a particular segment.
DHCP reservation
An IP address that is set aside by a DHCP server for a specific network client, which is identified by its MAC address.
DHCP scope
A shortage of available IP addresses on a network so that no new clients can connect to the network.
DHCPv6
The version of DHCP used with IPv6.
dig (domain information groper)
A utility available on Linux and macOS that provides more detailed domain information than nslookup. Use dig to query DNS nameservers for information about host addresses and other DNS records.
DKIM (DomainKeys Identified Mail)
An authentication method that uses encryption to verify the domain name of an email’s sender.
DMZ (demilitarized zone)
An area on the perimeter of a network that is surrounded by two firewalls—an external firewall that is more porous to allow more types of access, and an internal firewall that is more hardened to provide greater protection to the internal network.
DNAT (Destination Network Address Translation)
A type of address translation in which a gateway has a pool of public IP addresses that it is free to assign to a local host whenever the local host makes a request to access the Internet.
DNS (Domain Name System or Domain Name Service)
A hierarchical way of tracking domain names and their addresses, devised in the mid-1980s.
domain name
The last two parts of an FQDN, such as mycompany.com. Usually, a domain name is associated with the company’s name and its type of organization, such as a university or military unit.
DNS zone
A portion of the DNS namespace for which one organization is assigned authority to manage.
dual stacked
A type of network that supports both IPv4 and IPv6 traffic.
dynamic IP address
An IP address that is assigned to a device upon request and may change when the DHCP lease expires or is terminated.
elevated Command Prompt
A Command Prompt window with administrative privileges.
EUI-64 (Extended Unique Identifier-64)
The IEEE standard defining 64-bit physical addresses. In the EUI-64 scheme, the OUI portion of an address is 24 bits in length. A 40-bit extension identifier makes up the rest of the physical address, for a total of 64 bits.
exhausted DHCP scope
A shortage of available IP addresses on a network so that no new clients can connect to the network.
extension identifier
A unique set of characters assigned to each NIC by its manufacturer.
firewall
A device (either a router, a dedicated device, or a computer running special software) that selectively filters or blocks traffic between networks.
forward zone
A DNS lookup file that holds A records.
forwarding DNS server
An optional server that receives queries from local clients but doesn’t work to resolve the queries.
FQDN (fully qualified domain name)
A host name plus domain name that uniquely identifies a computer or location on a network.
gateway
A computer, router, or other device that a host uses to access another network. Gateways perform connectivity, session management, and data translation, so they must operate at multiple layers of the OSI model.
global address
An IPv6 address that can be routed on the Internet. These addresses are similar to public IPv4 addresses. Most global addresses begin with the prefix 2000::/3, although other prefixes are being released.
H.323
A signaling protocol used to make a connection between hosts prior to communicating multimedia data. H.323 has largely been replaced by SIP, which is easier to use.
host ID
The portion of an IP address that identifies the host on a network.
host name
The first part of an FQDN, such as www or ftp, which identifies the individual computer on the network.
IANA (Internet Assigned Numbers Authority)
A nonprofit, U.S. government-funded group that was established at the University of Southern California and charged with managing IP address allocation and the Domain Name System. The oversight for many of IANA’s functions was given to ICANN in 1998; however, IANA continues to perform Internet addressing and Domain Name System administration.
ICANN (Internet Corporation for Assigned Names and Numbers)
The nonprofit corporation currently designated by the U.S. government to maintain and assign IP addresses.
ICMP (Internet Control Message Protocol)
A core protocol in the TCP/IP suite that notifies the sender when something has gone wrong in the transmission process and packets were not delivered.