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