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Core Network Services

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verickle's version from 2018-08-31 18:40

Subnetting IPv6

Question Answer
Global routing prefixA 48-bit field beginning with the 001 FP value, the hierarchical structure of which is left up to the regional Internet registry (RIR)
Subnet IDA 16-bit field that organizations can use to create an internal hierarchy of subnets
Interface IDA 64-bit field identifying a specific interface on the network
One-level subnetBy setting all subnet ID bits to 0, all the computers in the organization are part of a single subnet.
Two-level subnetBy creating a series of 16-bit values, you can split the network into as many as 65,536 subnets. This is the functional equivalent of IPv4 subnetting, but with a much larger subnet address space.
Multi-level subnetBy allocating specific numbers of subnet ID bits, you can create multiple levels of subnets, sub-subnets, and sub-sub-subnets, suitable for an enterprise of almost any size.
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DHCP MESSAGE TYPE

Question Answer
DHCPDISCOVERUsed by clients to request configuration parameters from a DHCP server
DHCPOFFERUsed by servers to offer IP addresses to requesting clients
DHCPREQUESTUsed by clients to accept or renew an IP address assignment
DHCPDECLINEUsed by clients to reject an offered IP address
DHCPACKUsed by servers to acknowledge a client’s acceptance of an offered IP address
DHCPNAKUsed by servers to reject a client’s acceptance of an offered IP address
DHCPRELEASEUsed by clients to terminate an IP address lease
DHCPINFORMUsed by clients to obtain additional TCP/IP configuration parameters from a server
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DHCP EXTENSIONS

Question Answer
Requested IP AddressUsed by the client to request a particular IP address from the server
IP Address Lease TimeSpecifies the duration of a dynamically allocated IP address lease
Server IdentifierSpecifies the IP address of the server involved in a DHCP transaction; used by the client to address unicasts to the server
Parameter Request ListUsed by the client to send a list of requested configuration options (identified by their code numbers) to the server
MessageUsed to carry an error message from the server to the client in a DHCPNAK message
Renewal (T1) time valueSpecifies the time period that must elapse before an IP address lease enters the renewing state
Rebinding (T2) time valueSpecifies the time period that must elapse before an IP address lease enters the rebinding state
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DNS Zone Types

Question Answer
Primary zoneContains the master copy of the zone database, where administrators make all changes to the zone’s resource records
Secondary zoneContains a backup copy of the primary master zone database file, stored as an identical text file on the server’s local drive
Stub zone A copy of a primary zone that contains the key resource records that identify the authoritative servers for the zone
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Resource records

Question Answer
SOA (Start of Authority)Indicates that the server is the best authoritative source for data concerning the zone. Each zone must have an SOA record and only one SOA record can be in a zone.
NS (Name Server)Identifies a DNS server functioning as an authority for the zone. Each DNS server in the zone (whether primary master or secondary) must be represented by an NS record.
A (Address)Provides a name-to-address mapping that supplies an IPv4 address for a specific DNS name. This record type performs the primary function of the DNS: converting names to addresses.
AAAA (Address)Provides a name-to-address mapping that supplies an IPv6 address for a specific DNS name. This record type performs the primary function of the DNS: converting names to addresses.
PTR (Pointer)Provides an address-to-name mapping that supplies a DNS name for a specific address in the in-addr.arpa domain. This is the functional opposite of an A record, used for reverse lookups only.
CNAME (Canonical Name)Creates an alias that points to the canonical name (that is, the “real” name) of a host identified by an A record. Administrators use CNAME records to provide alternative names by which systems can be identified.
MX (Mail Exchanger)Identifies a system that will direct email traffic sent to an address in the domain to the individual recipient, a mail gateway, or another mail server.
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