1.6 Explain the use and purpose of network services.

The Start of Authority (SOA)

record identifies a primary authoritative name server that maintains complete resource records for a zone.

An NS (Name Server)

record identifies a server as a name server for a zone, but it does not indicate its authoritative status.

A Mail Exchange (MX)

record identifies an email server for the domain. An _____ record must not point to a CNAME record.

A Service (SRV)

record is a DNS record which identifies a record that provides a network service or protocol. Properties of this record type include port and protocol.

A Canonical Name (CNAME)

record is a Domain Name System (DNS) record used to represent an alias for a host. Aliases are used to give a host multiple names.

AAAA

record is used to resolve a host name to an Internet Protocol version 6 (IPv6) address.

A TXT

record is used to store any free-form text needed to support other network services. An SPF record, for example, is a _______ record that is used to list the IP addresses or names of servers that are permitted to send email.

External domain name system (DNS) zones

refer to records that Internet clients must be able to access.

Internet Protocol (IP) exclusions

is a feature of the Dynamic Host Configuration Protocol (DHCP) service. It excludes addresses from a DHCP pool that are used for static configuration of certain services in the same subnet range.

A media access control (MAC) address reservation

is a mapping of a MAC address to a specific IP address within the DHCP server's address pool.

The reverse lookup zone

is found in a special domain called in-addr.arpa of a Domain Name System (DNS) server. It contains PTR records to resolve IP addresses to name records (e.g. A record).

A root

is not a record type but is a server type. _____domain name system (DNS) servers have complete information about top-level domain servers.

The address pool

is the range of IP addresses that a DHCP server can allocate to clients.

A forward lookup zone

is used to translate a given a name record and return a related Internet protocol (IP) address.

Internal domain name system (DNS) zones

refer to the domains used on a private network. As the site uses the same domain name as AD, an A record for ftp needs to be created internally to point to the public ftp server address.

External DNS servers

refers to an ___________________with zone that Internet clients must be able to access. A company will most likely not have an ___________________with a public IP address.

The IP helper

refers to the DHCP relay configurations set on a router to forward DHCP requests to the appropriate DHCP server for processing.

Incorrect DNS records

will cause problems with the name resolution of host systems but will not impact a zone transfer.

DORA process

Discover, Offer, Request, Acknowledge

An A record

Is used to resolve a host name to an IPv4 address. This is the most common type of record in a DN

Stratum 1

NTP servers directly connect to an accurate clock source. If an inaccurate Network Time Protocol (NTP) server is specified on a server, it may result in time synchronization and further communication problems.

internal DNS server

because it controls all its services and applications. The DNS server will provide name resolution using FQDNs.

A DHCP relay agent

can be configured to provide forwarding of DHCP traffic between different subnets.

an ARP message

checks that the address is unused.

A client can attempt to rebind the same lease

configuration with any available DHCP server. By default, this happens after 87.5% of the lease duration is up (T2 timer).

A scope

defines a range or ranges of addresses that a dynamic host configuration protocol (DHCP) server can issue to client systems.

Client systems can use a

dynamically assigned IP address. This is an address assigned by a dynamic host configuration protocol (DHCP) server that may change when the assigned lease time is up.

Using a reservation

ensures a device always uses the same IP address. A lease period determines how long a system is assigned an IP address from a DHCP server. A long lease means the client does not have to renew as frequently, but as a result the DHCP server's pool of IP addresses is not replenished.

A PTR record

found in reverse lookup zones and is used to resolve an IP address to an associated host name.

A client can renew its lease

from a Dynamic Host Configuration Protocol (DHCP) server when at least half the lease's period has elapsed (T1 timer) so that it keeps the same IP addressing information.

Third-party domain name system (DNS)

means that another organization is responsible for hosting records. Typically, this would be for external domains.

A recursive lookup

means that if the queried server is not authoritative, it does take on the task of querying other name servers until it finds the requested record or times out.

A missing root server

might cause failure in a DNS lookup but would not impact a zone transfer.

DNS caching

occurs in both servers and client computers. )_______helps to speed the name resolution process by _______ host names. If a _______ cannot resolve a name, then a lookup is performed.

Media Access Control (MAC) reservations

or IP reservations are a mapping of a MAC address to a specific IP address within the DHCP server's address pool.

pointing to the correct Domain Name System (DNS)

server will provide proper name resolution.

Dynamic host configuration protocol (DHCP)

servers use scope options to issue configuration options, such as DNS server settings and more.

Time to live (TTL)

settings refer to the configuration of caching host names. When the ______ expires, the cache entry is invalid.

A system, such as a printer, can use a

static assignment. Typically this is done by using IP addresses outside the DHCP scope. Alternatively, a specially configured exclusion range can assign statically assigned addresses.

Forward lookups

to return an IP address associated with a host name. In this case, an entry for the particular host was likely missed or contains a typo.

A forwarder

transmits a client query to find a host to another domain name system (DNS) server and routes the replies it gets back to the client.