Chapter 9: Network Naming

Question 1

Define: Name Resolution

Answer 1

A process that automatically converts computer names to logical addresses (IP address) or physical addresses (MAC addresses)

Question 2

Define: Domain Name System (DNS)

Answer 2

A name resolution protocol used on all TCP/IP networks that resolves domain names to IP addresses.

Question 3

Define: Server Message Block (SMB)

Answer 3

A Layer 7 protocol that supports sharing folders and files.

Question 4

SMB
Port #

Answer 4

TCP port: 445

Question 5

What are the two halves of DNS?

Answer 5

Resolvers and name servers (DNS servers)

Question 6

What do DNS resolvers do?

Answer 6

Query name servers with a name to get its associated IP address.

This is called a recursive lookup.

Question 7

What do DNS name servers do?

Answer 7

They hold the actual name and IP DNS records in a database called a zone.

Question 8

How are the DNS name servers arranged?

Answer 8

In a hierarchical, interlinked fashion, with DNS root servers dispersed around the world.

Question 9

What do DNS root servers do?

Answer 9

They delegate name resolution to more-specific DNS systems.

Question 10

What do Top-Level Domain (TLD) servers do?

Answer 10

They handle the top-level domain (TLD) names, such as .com, .org, .net, .edu, .gov, .mil, .int, and delegate to domain-specific name servers (authoritative name servers).

Question 11

What do domain specific name servers (authoritative name servers) do?

Answer 11

They hold the domain’s zone that stores the actual IP addresses a computer needs to communicate with a domain’s servers.

These are the domain names such as google in www.google.com.

Question 12

What is a Fully Qualified Domain Name (FQDN)?

Answer 12

A complete DNS name, including the host name and all its domains in order.

It is written left to right with the host name first, then the domains in order moving up the DNS tree, to the root on the far right.

ex. www.google.com. (Internet FQDN)
ex. george-wks.sales.dallas. (Network FQDN)

Question 13

What is a name server?

Answer 13

A name server is software that responds to queries about DNS zones.

A single name server can be authoritative for one or more domains.

Question 14

What is a DNS zone?

Answer 14

A zone is a container for a single domain that gets filled with records.

Question 15

What is a DNS record?

Answer 15

A record attaches a piece of data to a name in the DNS tree. There are different types of records used.

Question 16

What is a zone transfer?

Answer 16

In a network with a primary name server and one or more secondary name servers, a zone transfer is a process that propagates new records to the other name servers in the network.

Question 17

What do name servers need to know about the other name servers within a network?

Answer 17

The name and IP address of the primary name server, as well as the name and address of every secondary name server.

Question 18

What name server in a network with multiple name servers, is the authoritative name server for that network?

Answer 18

The primary name server.

Question 19

What is the serial field in a DNS name server?

Answer 19

A special value that gets advanced when new data is added to a name server.

Secondary name servers check to see if their serial field matches the primary name server’s serial field to know if they need to request a zone transfer for updated data.

Question 20

What is a forward lookup zone for DNS?

Answer 20

It enables a system to determine an IP address by knowing the FQDN.

Question 21

What is a reverse lookup zone for DNS?

Answer 21

It enables a system to determine an FQDN by knowing the IP address.

A few low-level functions (like mail) and some security programs depend on reverse lookup zones.

Question 22

In a Windows command prompt, what do you type to see a host’s DNS cache?

Answer 22

ipconfig /displaydns

Question 23

What is a DNS recursive lookup?

Answer 23

A request from a client to it’s DNS server for the IP address attached to a FQDN.

Question 24

What is a DNS iterative lookup?

Answer 24

The whole process of a client’s DNS server asking each name server from the root down.

Question 25

Define: Internal DNS Server

Answer 25

A name server that hosts zones for a private network. It is used for internal queries from internal clients and caching.

Question 26

Define: External DNS Server

Answer 26

A name server that hosts zones for Internet sites and is located outside an internal network.

Question 27

Define: DNS record type - SOA (Start Of Authority)

Answer 27

Every zone requires an SOA record that defines the primary name server in charge of the zone.

Question 28

Define: DNS record type - NS (Name Server)

Answer 28

An NS record points to the server that holds the records (zone) for a part of the DNS tree. NS records enable the name servers to know where to point the resolvers to find the authoritative name servers for a specific domain below them in the DNS hierarchy.

Question 29

Define: DNS record type - A (Address)

Answer 29

An A record holds the IPv4 address for a host.

Question 30

Define: DNS record type - AAAA (Quad A)

Answer 30

An AAAA record holds the IPv6 address for a host. The four A letters signify that IPv6 addresses are four times longer than IPv4 addresses (128 bits vs. 32 bits).

Question 31

Define: DNS record type - CNAME (Canonical Name)

Answer 31

A CNAME record holds the FQDN for an alias that is used.

Question 32

Define: DNS record type - PTR (Pointer)

Answer 32

A PTR record reverses the functions of A or AAAA records, and are found only in reverse lookup zones. They use an IP address for their names and hold the FQDN of a host at that address.

Question 33

Define: DNS record type - MX (Mail Exchange)

Answer 33

MX records hold the FQDN of the server that handles mail for the domain. SMTP servers use MX records exclusively to determine where to send mail.

Question 34

Define: DNS record type - SRV (Service)

Answer 34

A SRV record is a generic DNS record that supports any type of server by specifying the location of services.

Question 35

Define: DNS record type - TXT (Text)

Answer 35

A TXT record is a freeform type of record that can be used for anything. One use is to enable domains to verify that e-mail being received by a third-party e-mail server is sent by a legitimate server within the domain to help secure against e-mail spoofing.

Question 36

What does the Dynamic DNS (DDNS) protocol do?

Answer 36

It enables DNS servers to get automatic updates of the IP addresses for the computers in their forward lookup zones by communications with the local DHCP server.

Question 37

What is the DNS Security Extensions (DNSSEC) protocol and what does it do?

Answer 37

It is an authorization and integrity protocol that prevents the impersonation of legitimate DNS servers.

Question 38

What do you type in a Windows command prompt to flush the local system's DNS cache?

Answer 38

ipconfig /flushdns

Question 39

What do you type in a Windows command prompt to enable DNS server queries?

Answer 39

nslookup [IP address or FQDN] [optional DNS server IP address]