IS 460 Chapter 3

Ways the resolution process can get more complex

Caching server typically is not the same machine as the authoritative server name servers within a company might not have access to root servers A TLD name server might be aware of an intermediate name server rather than the authoritative name server

How to Fix DHCP issues?

Check the settings on your DHCP server Make sure the DHCP scope is large enough to account for the number of clients the network must support consider implementing a shorter lease time on larger networks

Public IP addresses

Classes A, B, and C licensed IP addresses available for use on the internet

Port Address Translation (PAT)

Process of assigning a TCP port number to each ongoing session between a local host and Internet host

Open Source

Software whose source code is freely available and may be used, distributed, or modified by anyone.

Steps for Auto configuration for IPv6

Step 1 - the computer creates is IPv6 address Step 2 - the computer checks to make sure its IP address is unique on the network Step 3 - The computer asks if a router on the network can provide configuration information

Authoritative server

The authority on computer names and their IP addresses for computers in their domains.

port number, mac address, ip address, FQDNs

The four addressing methods

Interface ID

The last 64 bits, or four blocks, of an IPv6 address that uniquely identify the interface on the local link.

Name resolution

The process of discovering the IP address of a host when the FQDN is known

ICMPv6

The version of ICMP used with IPv6 networks.

neighbors

Two or more nodes on the same link.

ping6

for Linux computers running IPv6, used to verify whether an IPv6 host is available

Command-link tools

great resource to troubleshoot network problems Most helpful tools: ping ipconfig (Windows only) ifconfig (Linux only) nslookup dig (Linux only)

IPv6 address

has 128 bits written as eight blocks of hexadecimal numbers, each block is 16 bits, if blocks contain all zeroes, they can be written as double colons (::), only one set of double colons is used per one of these

name servers

hold databases, which are organized in a hierarchical structure any of the server types can co-exist on the same machine

top-level domain (TLD) servers

hold information about authoritative servers owned by various organizations

CNAME (Canonical name record)

holds alternative names for a host

TXT (text) record

holds any type of free-form text

MX (Mail Exchanger) record

identifies a mail server and is used for email traffic

Unicast address

identifies a single node on a network

SRV (service) record

identifies the hostname and port of a computer that hosts a specific network service besides email

NS (Name server) record

indicates the authoritative name server for a domain

top-level domain (TLD)

last part of an FQDN

BIND (Berkely Internet Name Domain)

most popular dns server software

3 DNS elements

namespace name servers resolvers

ping -6

on windows computer running IPv6, use to verify connectivity on IPv6 networks

Event Viewer

one of the first places to start looking for clues when something goes wrong

Multicast address

packets are delivered to all nodes on a network Address prefix: FF00::/8, first 8 bits are always 1111 1111

Address Translation

process where a gateway device substitutes the private IP addresses with its own public address

ICMP (Internet Control Message Protocol)

protocol used by the echo request/reply to carry error messages and information about the network

Forwarding DNS server

receives queries from local clients but doesn't work to resolve the queries

ICANN

restricts what type of hosts can be associated with .arpa, .mil, .int, .edu and .gov

ipconfig

shows current TCP/IP addressing and domain name information on a windows computer use ipconfig/all to see more complete summary of TCP/IP addressing information

If the computer is not obtaining IP address and related information from a DHCP server

static settings might be using the wrong information try switching to DHCP

A (address) record

stores the name-to-address mapping for a host

Network Address Translation (NAT)

technique designed to conserve public IP addresses needed by a network

Noninteractive nslookup

test a single DNS server

Primary DNS server

the authoritative name server for the organization holds the authoritative DNS database for the organization's zones

DNS zone

the domains that the organization is responsible for managing

Static (or Source) Network Address Translation (SNAT)

the gateway assigns the same public IP address to a host each time it makes a request to access the internet

Dynamic Network Address Translation

the gateway has a pool of public addresses that it is free to assign to a local host when it makes a request to access the Internet

Port numbers

these ensure data is transmitted to the correct process among multiple processes running on the computer

reverse DNS lookup

to find the host name of a device whose IP address you know

interactive nslookup

to test multiple DNS servers at one time

exit

type this to exit nslookup's interactive mode

PTR (Pointer) record

used for reverse lookups

ipconfig utility

used in a command prompt to find out current TCP/IP settings

Subnet mask

used to indicate what portion of an IP address is the network portion (network ID) and what part is the host portion (host ID)

ping (Packet Internet Groper)

used to verify that TCP/IP is installed, bound to the NIC, configured correctly, communicating with the network sends out a signal called an echo request to another device other computer replies with echo reply

ifconfig

utility to view and manage TCP/IP settings for Linux

Auto configuration

when a computer autoconfigures its own link local IP address (IPv6 does this)

Dual stacked

when a network is configured to use both IPv4 and IPv6

Resolvers

A DNS client that requests information from DNS name servers.

Well-known ports

0-1023

Class A

1.x.y.z to 126.x.y.z 236 possible networks 16 million IP addresses in each network

Registered ports

1024-49151

Class B

128.0.x.y to 191.255.x.y 16000 possible networks 65000 number of IP addresses in each network

Class C

192.0.0.x to 233.255.255.x 2 million number of possible networks 254 number of IP addresses in each network

IPv4 address

32-bit address organized into four groups of 8 bits (known as octects), Each of the four octets can be any number from 0 to 255, Some IP addresses are reserved

MAC address

48 bits, first 24 bits OUI (Organizationally Unique Identifier) aka manufacturer-ID assigned by the IEE, last 24 bits make up the extension identifier or device ID, which is assigned to the NIC by the manufacturer

Dynamic and private ports

49152-65535

Application layer addressing method

FQDNs, computer names, and host names

internel and external DNS queries should be handled by different DNS servers can use a firewall to filter or block traffic between networks

For a more secure network

AAAA (Address) record

Holds the name-to-address mapping for IPv6 type IP address

Network layer addressing method

IP address

Dynamic IP address

IP address assigned automatically by a DHCP (dynamic host configuration protocol) server

Static IP address

IP address assigned manually by the network administrator

Network Connection Configuration issues

Incorrect netmask Incorrect gateway Duplicate address

Data link layer addressing method

MAC address

tunneling

a method used by IPv6 to transport IPv6 packets through or over an IPv4 network

Recursive DNS Server

a query that demands a resolution or the answer "It can't be found"

iterative DNS server

a query where the local server issues queries to other servers other servers only provide information if they have it do not demand a resolution

FQDN (Fully Qualified Domain Name)

a unique character-based name for an IP address

Caching DNS server

accesses the public DNS data and caches the DNS information it collects

nslookup (name space lookup)

allows you to query the DNS database from any computer on a network to find the host name of a device by specifying its IP address, or vice versa useful for verifying a host is configured correctly or for troubleshooting DNS resolution problems

IANA

an organization responsible for tracking the assignments of domain names, port numbers, and IP addresses

Link (local link)

any LAN bounded by routers (an interface is a node's attachment to one of these)

DNS server

application layer client-server system of computers and databases responsible for tracking computer names and their IP addresses

DMZ (demilitarized zone)

area between two firewalls

dig (domain information groper)

available on Linux and macOS provides more detailed information than nslookup and uses more reliable sources of information to output its result

secondary DNS server

backup authoritative name server for the organization

Class D

begin with octets 224-239 and are used for multicasting

Class E

begin with octets 240-254 and are used for research

Microsoft DNS Server

built-in DNS service in the Windows Server OS

global unicast address

can be routed on the internet Address prefix: 2000::/3, first 3 bits are always 001

link local unicast address

can be used for communicating with nodes in the same link Address prefix: FE80::/64, first 64 bits are always 1111 1110 1000 0000 0000 0000 ... 0000

Anycast address

can identify multiple destinations, with packets delivered to the closest destination

What to do if computer displays incorrect time?

check a domain computer's time source from a command Prompt window by entering w32tm /query/ source

When a computer is struggling to establish a network connection

check its TCP/IP configuration settings

Prefix Discovery

computer uses the prefix to generate its own link local or global IPv6 address by appending its interface ID to the prefix

Socket

consists of host's IP address and the port number of an application running on the host, colon separates the two values ex: 10.43.3.87:23

Gateway

device that nodes use for access to the outside world

Classful Addressing

dividing line between the network and host portions is determined by the numerical range the IP address falls. Divided into five classes: A, B, C, D, E

Namespace

entire collection of computer names and their associated IP address stored in databases on DNS name servers around the globe