CompTIA Networks+ (Chapter 2)

DHCP reservation

A static IP address assigned by DHCP

NAT (Network Address Translation)

A technique designed to conserve the number of public IP addresses needed by a network.

Network layer IP address

An IP address is assigned to every interface, which is a network connection made by a node or host on a network. The IP address can be used to find hosts on any computer on the globe if the IP address is public on the Internet.

Packet analyzer (or protocol analyzer)

Analyzer to collect and examine network messages that use various protocols. Ex: Wireshark

BIND

Berkeley Internet Name Domain, the most popular DNS server software, which is free, open source software that runs on Linux, UNIX and Windows platforms

Socket address

Consists of a host's IP address and the port number of an application running on the host, with a colon separating two values. Ex: 10.43.3.87:23

0.0.0.0

Currently unassigned

DNS distributed database model

DNS doesn't follow a centralized database model, but rather a distributed database model

DMZ

Demilitarized zone, the area between two firewalls

Split DNS

Design, that also called a split-horizon DNS, in which internal and external DNS queries are handled by different DNS servers or by a single DNS server that is specifically configured to keep internal and external DNS zones separate.

Well-known ports

Ports range from 0 to 1023 and are assigned by IANA to widely used and well-known protocols and programs, such as FTP, Telnet, and HTTP.

Registered ports

Ports range from 1024 to 49151 and can be used by network users and processes that are not considered standard processes. Default assignment of these ports must be registered by IANA.

Dynamic and private ports

Ports range from 49152 to 65535 and are open for use without restriction. Dynamic port is a port number that can be assigned by a client or server as the need arises. A private port number is a port assigned by the network administrator that is different from a well-known port number for that service.

NetBIOS over TCP/IP (NetBT or NetBIOS)

Protocol that allows old applications designed for out-of-date NetBIOS networks to work on TCP/IP networks.

TFTP (Trivial File Transfer Protocol)

Protocol that is seldom used by humans. Computers commonly use it as they are booting up to request configuration files from another computer on the local network. This protocol uses the UDP transport protocol, whereas normal FTP uses the TCP transport protocol.

SMB (Server Message Block)

Protocol used by earlier Windows OSs for file sharing on a network. UNIX uses a version of SMB in its Samba software, which is used to share files with other operating systems, including Windows systems.

SIP (Session Initiation Protocol)

Protocol used to make an initial connection between hosts for transferring multimedia data. After the connection is established, another protocol is typically used - for example, VoIP is a video conference. This protocol is a type of signaling protocol, which is a protocol that makes an initial connection between hosts but that does not actually participate in data exchange.

SNMP (Simple Network Management Protocol)

Protocol used to monitor and manage network traffic

NTP (Network Time Protocol)

Protocol used to synchronize clocks on computers on a network.

Iterative query

Queries that do not demand a resolution. For example, when the local server issues queries to other servers, which means the other servers only provide information if they have it.

127 IP address

Reserved for research and loopback addresses

DNS servers

Servers responsible for tracking computer names and their IP Addresses

MGCP (Media Gateway Control Protocol)

Signaling protocol used to communicate multimedia data.

H.323

Signaling protocol used to make a connection between hosts prior to communicating multimedia data. H.323 has largely been replaced by SIP, which is easier to use.

ICANN

The Internet Corporation for Assigned Names and Numbers

Data Link layer MAC address

The MAC address, also called the physical address, is embedded on every NIC on the globe and is assumed to be unique to that NIC. Nodes on a LAN find each other using their MAC addresses. However, MAC addresses are not used to find nodes on networks other than the local network.

DNS zone

The domains that the organization is responsible for managing. Large organizations can keep all its domains in a single zone, or it can subdivide its domains into multiple zones to make each zone easier to manage

SNAT (Static Network Address Translation)

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

PAT (Port Address Translation)

The gateway device uses this process to assign a separate TCP port number to each ongoing conversation, or session, between a local host and an Internet host

DNAT (Dynamic Network Address Translation)

The gateway has a pool of public IP Addresses that it is free to assign to a local host whenever the local host makes a request to access the Internet

Internet Assigned Numbers Authority (IANA)

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

Name resolution

The process of discovering the IP address of a host when you know its fully qualified domain name

IPv4 and IPv6

Two types of IP addresses used on the Internet

255.255.255.255

Used to broadcast messages by TCP/IP background processes; a broadcast message is read by every node on a network

ipconfig or ipconfig /all

Windows utility in a Command Prompt window to find out the current TCP/IP settings

CNAME (Canonical Name) record

holds alternative names for a host

MX (Mail Exchanger) record

identifies a mail server and is used for email traffic

PTR (Pointer) record

is used to reverse lookups, to provide a host name when you know its IP address

A (Address) record

stores the name-to-address mapping for a host. This resource record provides the primary function of DNS - to match host names to IP addresses, using IPv4 addresses

AAAA (Address) record

(called a "quad-A record") holds the name-to-address mapping, but the IP address is an IPv6 type IP address

Namespace database resource records

*** A (Address) record stores the name-to-address mapping for a host. This resource record provides the primary function of DNS - to match host names to IP addresses, using IPv4 addresses *** AAAA (Address) records (called a "quad-A record") also holds the name-to-address mapping, but the IP address is an IPv6 type IP address *** CNAME (Canonical Name) record holds alternative names for a host ***PTR (Pointer) record is used to reverse lookups, to provide a host name when you know its IP address *** MX (Mail Exchanger) record identifies a mail server and is used for email traffic

Gateway

A computer, router, or other device that a host uses to access another network.

Firewall

A device, either a router or a computer running special software, that selectively filters or blocks traffic between networks.

Address translation

A gateway device or a router that stands between a private network and other networks substitutes the private IP addresses used by computers on the private network with its own public IP address when these computers need access to other networks or the Internet

Private port

A port number assigned by the network administrator that is different from a well-known port number for that service.

Transport layer port numbers

A port number identifies one application among several applications that might be running on a host and is used by the Transport layer to find an application.

Dynamic port

A port number that can be assigned by a client or server as the need arises.

Zone transfer

A process when a secondary DNS server needs to update its database so it makes the request to the primary server for the update. Caching-only DNS servers do not participate in this process, which helps reduce network traffic on slow links in intranets where these servers are often used.

Recursive query

A query that demands a resolution or the answer "It can't be found". For example, the initial request the resolver makes to the local server is a ... query

DHCP scope

A range of IP addresses to be assigned to clients when they request an address

Subnet mask

A 32-bit number that helps one computer find another

top-level domains (TLD)

.com, .org, .net, etc..

Four addressing methods of the OSI model (starting from the top)

1. Application layer FQDN, computer names, and host names 2. Transport layer port numbers 3. Network layer IP address 4. Data Link layer MAC address

Class A IP address

1.x.y.z to 126.x.y.z

Class B IP address

128.0.x.y to 191.255.x.y

Class C IP address

192.0.0.x to 223.255.255.x

Private IP addresses range

-10.0.0.0 through 10.255.255.255 -172.16.0.0 through 172.31.255.255 -192.168.0.0 through 192.168.255.255

DNS

Domain Name System or Domain Name Service was designed to associate computer names with IP addresses. DNS is an Application layer client-server system of computers and databases made up of these elements: - namespace (is the entire collection of computer names and their associated IP addresses stored in databases on DNS name servers around the globe) - name servers (or DNS servers, hold these databases, which are organized in a hierarchical structure) - resolvers (is a DNS client that requests information from DNS name servers)

DDNS

Dynamic DNS

DHCP

Dynamic Host Configuration Protocol

Application layer FQDN, computer names, and host names

Every host on a network is assigned a unique character-based name called the fully qualified host name or the fully qualified domain namer (FQDM). In the example john.mycompany.com, "john" is the host name, which identifies the individual computer on the network. "mycompany.com" is called the domain name, which matches the name of the organization's domain or network. "ftp" in ftp.mycompany.com is the host name usually given to an FTP server. "www" in www.mycompany.com is typically the host name assigned to a computer running a Web server. FQDM is sometimes called the computer name and, more loosely, it is simply called the host name.

Default gateway

Gateway device that nodes on the network turn to first for access to the outside world.

Dynamic IP address

IP address assigned to a server from DHCP (Dynamic Host Configuration Protocol) each time it connects to the network

IPv6

IP addresses that have 128 bits and are written as eight blocks of hexadecimal numbers. As an example, 2001:0DB8:0B80:0000:0000:00D3: 9C5A:00CC

IPv4

IP addresses that have 32 bits and are written as four decimal numbers called octets. As an example, 92.106.50.200

APIPA (Automatic Private IP Addressing)

If a computer configured to use DHCP first connect to the network and is unable to lease an IPv4 address from the DHCP server, it uses this address in the address range 169.254.0.1 through 169.254.255.254

127.0.0.0

Indicates your own computer and is called the loopback address

MAC Address

Media Access Card address (physical address) is stamped directly onto the NIC. It contains two parts, is 48 bits long and is written as hexadecimal numbers separated by colons. As an example, 00:60:8C:00:54:99. The first 24 bits (00:60:8C) are known as OUI (Organizationally Unique Identifier) or block ID or company-ID, and identifies the NIC's manufacturer. The last 24 bits make up the extension identifier or device ID and identify the device. Manufacturers assign each NIC a unique extension identifier, based on the NIC's model manufacture date, so that no two NICs share the same MAC addresses.

Class D IP address

Not available for general use. Begin with octets 224 through 239 and are used for multicasting, in which one host sends messages to multiple hosts, such as when a host transmits a videoconference over the Internet

Class E IP address

Not available for general use. Begin with octets 240 through 254. Reserved for research.

Static IP address

Permanently assigned IP address

Time to Live

a field that identifies how long the record should be saved in a cache on a server, and is included in zone transfers