Chapter 10: Network Naming Pg 341 - 346

CIFS

• a computer uses a CIFS broadcast to get the name of another computer
• organizes computers on a network into groups
• workgroup: a name that organizes a group of computers
• all computers within a domain authenticate to the domain controller when they log in 
• Active Directory: an organization of related computers that shares one ore more windows domains
• has no single domain controller

Chapter 10: Network Naming pg 326 - 340

Name Servers

• DNS Server: a computer running DNS sever software
• zone: a container for a single domain that gets filled with records
• record: a line in the line zone data that maps an FQDN to an IP address 
• systems running DNS server software store the DNS information
• when a system needs to know the IP address for a specifc FQDN, it queries the DNS server listed in the TCP/IP configuration
• Authoritative DNS server: a simple network usually has one DNS server for the entire network
• job is to make sure that all the other name servers are updated for changes
• a DNS server has a signle zone that lists all the host names on the domain and their corresponding IP addresses
• a single DNS domain may have a single authoritative DNS server but a number of other DNS servers 

Name Resolution

• a web browser must resolve the name to the web server's IP address to make a connection to that web server
• can be resolved in three ways
• broadcasting
• consulting the locally stored HOSTS text file
• contacting a DNS server
• to broadcast, the host sends a message to all the machines on the network 
• works for small networks 
• limited because it cannot provide name resolution across routers
• routers do not forward broadcast messages to other networks
• a HOSTS file lists the names and addresses of machines on a network 

Network + Practice Exam

Test Taken
Score Given: 6/25

Things To Remember:

1. nslooup is used for querying DNS servers to obtain domain name or IP address mapping
2. HTTPS uses SSL/TLS on TCP port 443
3. In transport mode, IPsec offers encryption.
4. TCP port 20 is used for FTP data transfer.
5. Coaxial cabling is used with BNC connectors.
6. IPv6 addresses consist of 128 bits.
7. Layer 2 tunneling Protocol offers no encryptions used with IPsecruns over UDP port 1701
8. Network Time Protocol uses UDP port 123
9. Smurf attack is an example of a Distributed Denial of Service attack.
10. CSMA/CA is the name of an access method used in wireless networks.
11. Fake logon screen on a system will most probably be a result of downloading and installing a trojan horse.
12. Internet Group Management Protocol is used for establishing multicast group memberships used on IPv4 networks.
13. IMAP4 runs on TCP 143 and is used for retrieving e-mail messages from e-mail servers.
14. MAC address's consist of 48 bits and is also known as a physical address.
15. CSMA/CD is used as an access method used in ethernet networks.
16. 802.3ae defines 10 Gigabit Ethernet

Chapter 10: Network Naming pg 317 - 322

How DNS Works 
- DNS servers use UDP port 53 and sometimes TCP port 53
- the DNS root for the entire internet consists of 13 powerful DNS server clusters all over the world
        -> has the complete definitive name resolution table
- Internet Corporation for Assigned Names and Numbers (ICANN): creates new TLDs 

Name Spaces 
- Hierarchical Name Space (used by DNS): an imaginary tree structure for possible names that can be used within a single system
       -> enables administrators to give networked systems longer names
- Flat Name Space (used by HOSTS): an undivided list containing all names
       -> all names must be absolutely unique

Chapter 9: TCP/IP Applications Pg 301 - End

Rlogin, RSH, and RCP
- Remote Login (Rlogin): you can connect and run commands by running the program with the host name of the server
       -> can configure it to log in automatically without needing to enter a username and password
       -> only connects using UNIX hosts
- Remote Shell (RSH): enables you to send single commands to the remote server
        -> runs over TCP port 514 by default
- Remote Copy Protocol (RCP): provides the capability to copy files to and from the remote server without needing FTP or NFS 

SMTP, POP3, AND IMAP4
- Simple Mail Transfer Protocol (SMTP): used to send e-mail
- Post Office Protocol 3 (POP3): receives e-mail from SMPT using TCP port 110
- Internet Message Access Protocol 4 (IMAP4): retrieves e-mail from an e-mail server
         -> enables you to search through your messages on the mail server to find specific keywords
         -> supports the concept of folders
       
File Transfer Protocol (FTP)
- original protocol used on the internet for transferring files
- can transfer while keeping security and data integrity
- uses TCP ports 21 and 20 by default

Things To Remember: 

1. Secure Sockets Layer (SSL) is a protocol developed by Netscape for transmitting private documents over the internet. SSL works by using a public key to encrypt sensitive data.
2. URLs that use an SSL connection start with HTTPS 
3. SSH encrypts data and is more secure than Telnet. SSH uses port 22.
4. Telnet is used to issue commands to a remote server

Chapter 9: TCP/IP Applications pg 286 - 300

Connection Status 
- open port: a socket that is prepared to respond to any IP Packets destined for that socket's port number
           -> every application has an open port
           -> to see all listening ports time netstat -an into a command prompt

Rules for Determining Good vs. Bad Communications

1. Memorize known ports for common TCP/IP applications 
2. Learn netstat such as -an, -n, -o, and -b
3. get rid of bad or unnecessary processes 

The World Wide Web

- composed of servers that s tore specially formatted documents using Hypertext Markup Language (HTML)

        -> many pages now are written using HTML5

- Extensible Markup Language (XML): provides the basic format or language for everything from application programming interfaces to word documents

HTTP

- Hypertext Transfer Protocol (HTTP): underlying protocol used by the web 

           -> relays commands executed by users without reference to any commands previously executed

Web Servers and Web Clients

- web server: a computer that delivers web pages

           -> listen on port 80 

- Internet Information Services (IIS): enables you to set a maximum connection limit on your web server based on available bandwidth and memory 

- uniform resource locator (URL): complete name of a web server

Secure Sockets layer and HTTPS
- Secure Sockets Layer(SSL): a protocol for transmitting private documents over the internet 

- Hypertext Transfer Protocol over SSL (HTTPS)

- Transport Layer Security (TLS)

Chapter 9: TCP/IP Applications pg 275 - 286

TCP
- Transmission control Protocol (TCP): enables connection-oriented communication in networks that use the TCP/IP protocol suite
- TCP three-way handshake
- most TCP/IP applications use TCP because connection-oriented sessions are designed to check for errors

DHCP
- Dynamic Host configuration Protocol
- can't assume another computer is ready on either side of the session
- uses port 67 for sending data the the DHCP server

NTP/SNTP
- Network Time Protocol (NTP)
- Simple Network Time Protocol (SNTP)
- synchronize the clocks of devices on the network

TFTP
- Trivial File Transfer Protocol (TFTP): enables you to transfer files from one machine to another
- has no data protection so it is not used for communication between computers across the internet

ICMP
- works at layer 3 to deliver connectionless packets
- handles disconnect messages

IGMP
- Internet Group Management Protocol (IGMP): enables routers to communicate with hosts to determine a "group" membership

Registered Ports
- ports numbers from 1024 to 49151 are called registered ports
- anyone can use these port numbers for their servers
- 0 to 1023: well-known ports
- 1024 to 4951: Registered ports
- 49152 to 65535: dynamic or private ports
- socket: connection data stored on a single computer
- socket pairs: the connection data stored on two computers
- connection: the whole interconnection

Chapter 8: Routing Pg 259 - End

IS-IS
- Intermediate system to Intermediate System (IS-IS): allows you to use a link state dynamic protocol without using OSPF
- uses the concept of areas and send-only updates to routing tables

EIGRP - The Lone Hybrid 
- Enhanced Interior Gateway Routing Protocol (EIGRP)
- replaced Interior Gateway Routing Protocol (IGRP)

Set Up of the WAN
- need to know the network IDs for each side of the router
- WAN invariably connects to an ISP

Set Up the LAN
- need to choose a netowrk ID
- need to assign the correct IP information to the LAN-side NIC

Configure A Dynamic Protocol
- dynamic protocols are tied to indiviudal NICs
- make sure the two NICs are configured to use the same dynamic routing protocol

Things To Remember:

1. A router is a peice of hardware that forwards packets based on IP address
2. A router can interconnect different layer 2 technologies
3. Port Address Translation enables you to share a single public IP address with many computers
4. distance vector routing protocols use hop count to determine the best route.
5. OSPF bases routes on speed and sends only route changes to minimize traffic.
6. Area 0 is known as the backbone.
7. Yost cable was invented to standardize the serial console interface.

Chapter 8: Routing Pg 252 - 258

BGP
- autonomous system (AS): one or more networks that are governed by a single dynamic routing protocol within that system
        -> do not use IP addresses
        -> they use a globally unique Autonomous System Number (ASN)
        -> originally 16-bit but are now 32-bit broken into two separate 16-bit numbers broken by a dot (.)
        -> AS's communicate using Exterior Gateway Protocol (EGP)
        -> networks with an AS communicate using Interior Gateway Protocols (IGP)
- Border Gateway Protocol (BGP - 4): connects all of the Autonomous Systems on the internet
        -> BGP routers are manually configured
        -> supports policies for limiting which and how other routers may access an ISP
       
Link State
- link state dynamic routing protocol 
        -> OSPF
        -> IS-IS

OSPF
- Open Shortest Path First (OSPF)
        -> used on internal networks
        -> converges faster and more efficiently than RIP 
        -> not often found on home routers
- link state advertisements (LSAs) are sent out by OSPF capable routers
        -> forwarded to every OSPF router in the network
- every router in the network is assigned an area ID 
- designated router (DR): relays information to all of the other routers in the area
- backdup desginated router (BDR): used in the event the DR is not available
        -> the DR and BDR compete to become the DR during the inital LSA packet exchange
- flooding when a new router initially starts and sends out a plethora of LSAs
- cost of an OSPF is based off of 100,000,000/bandwidth in bps
         -> the faster the bandwidth the lower the cost
- scales to large networks and is supported by nearly all routers
- OSPF corrects link failures and creates convergence almost immediately

Chapter 8: Routing Pg 236 - 252

Network Address Translation 
- Network Address Transnation (NAT): hide the IP addresses of computers on the LAN but still enable those computers to communicate with the broader network

The Setup
- requires a block of unique IP addresses
- basic NAT: router replaces the source IP with its outside interface address on outgoing packets
- dynamic NAT: many computers can share a pool of routable IP addresses

Port Address Translation
- Port Address Translation (PAT): uses port numbers to map traffic from specific machines in the network
- when the receiving system sends the packet back it reverses the IP addresses and ports

Port Forwarding
- Static NAT: maps a single routable IP address to a single machine
- port forwarding: can designate a specific local address for various network services
     -> computers outside the network can request a service using the public IP address and the port number for the service
     -> can be used to hide a service hosted inside a network by changing the default port number

Configuring NAT
- by default, routers are set to Gateway which means NAT is turned on

Dynamic Routing
- routers have static routes 
- most routers have the capability to update their routes dynamically 

Routing Metrics
- metric: a relative value that routers use when they have more than one route to get to another network
- a router will choose the route with the lowest value IP address
- there is no single rule to set the metric value in a routing table
- Maximum Transmission Unit:
        -> determines the largest frame a particular technology can handle

Distance Vector
- Distance Router:
        -> calculate the total cost to get to a particular network ID and compare that cost to the total cost of all the other routes
- each distance vector routing protocol has a maximum number of hops that a router will send its routing table to keep traffic down
- convergence (steady state):  the updating of the routing tables for all the routers has completed

RIPv1
- Routing Information Protocol(RIP): has a maximum hop count of 15
- variable-length subnet masking (VLSM): networks connected through the router using different subnet masks

RIPv2
- current version of RIP
- VLSM has been added and authentication is built into the protocol
- obsolete for small private WANs that consist of a few routers

Chapter 8: Routing pg 228 - 234

How Routers Work
- router: any piece of hardware that forwards packets based on their destination IP address
- routers work at the Network Layer of the OSI model and the Internet level of the TCP/IP model
- routers are dedicated boxes that contain at least two connections
- router reads the IP addresses of the packets to determine where to send the packets
- routers examine packets and send the packets to the proper destination

Routing Tables
- router inspects each packet's destination IP address and then sends the IP packet out the correct port

- routing table: tells the router exactly where to send the packets
       -> each row in a routing table defines a single route
       -> each column identifies a specific criteria
       -> Destination LAN IP: a defined network ID. Every directly connected network ID is listed here
       -> Subnet  Mask: needed to define a network ID
            - router uses the combination of the destination LAN IP and subnet mask to see if a packet matches the   route
       -> Gateway: the IP address for the next hop router (where the packet will go next)
       -> interface: indicates to the router which port to use
- router compares the destination LAN IP address on each packet toe very listing in the routing table before sending the packet out
- default route tells the router exactly what to do with every incoming packet
- multihomed computers: computers with more than one NIC
- to view routing table type the command: netstat -r

Chapter 7: TCP/IP Basics pg 216 - End

Dynamic IP Addressing 
- Dynamic Host Configuration Protocol (DCHP)
      -> automatically assigns an IP whenever a computer connects to the network

How DHCP Works( Uses ports 67 and 68)
- DHCP Client
- automatically sens out a special DHCP discover packet using the broadcast address
- discover message searches for DHCP servers
- one system on the LAN must be running DHCP server software
- designed to respond to DHCP discover requests
- DHCP server is configured to pass out IP addresses from an IP range (scope)
- DHCP servers can be set up to reserve addresses for specific machines (reservations)
- DHCP client sends out a DHCP request
- DHCP server then sends  DHCP acknowledge and lists the MAC address and IP information
- DHCP lease: the acceptance from the DHCP client of the DHCP server's data
         -> set for a fixed amount of time (5-8 days)
         -> near the end of the lease time, the DHCP client simply makes another DHCP Discover message
- DHCP server looks at the MAC address information and gives the DHCP client the same IP info

Living with DHCP
- biggest issue: a DHCP client tries to get a DHCP address and fails
        -> indicated by the operating system posting some form of error and the DHCP client has a strange  IP address
- Automatic Private IP Addressing (APIPA) : generates the "special" IP address
        -> all DHCP servers generate an APIPA address automatically if they do not recieve a response to  a DHCP Discover message
        -> DHCP client only generates the last two octets of an APIPA address
        -> APIPA cannot issue a default gateway which prevents internet access
        -> systems that use static IP addressing can never have DHCP problems

What to Remeber:

1. An IPv4 address consists of 32 bits.
2. The network ID is the first three octets when using the specified subnet
3. A subnet is all 1s followed by 0s

Chapter 7: TCP/IP Basics Pg 200 - 216

Class IDs
- Internet Assigned Numbers Authortiy (IANA)
       -> formed to track and distribute IP addresses to those who need them
- American Registry for Internet Numbers (ARIN)
       -> American region of the IANA

 - multicast licenses are used fro one-to-many communciation
- broadcast: every computer on the LAN hears the message
- unicast: one computer on the LAN hears the message
- multicast: multiple computers on the LAN hear the message

CIDR Subnetting
- subnetting: taking a single class of IP addresses and chopping it up into multiple smaller groups

Subnetting
- enables more efficient use of IP addresses
- allows separation of a network for security
- can extend the subnet mask by adding more ones
- never subnet without converting to binary
- has two goals
        -> efficiency and making multiple network IDs

Calculating Hosts
-  2^x - 2 = number of hosts
        -> x = number of zeros in the subnet mask

Calculating Subnets
- start with a beginning subnet mask and extend the subnet extension as far as you need
- 2^y where y = number of bits you add to the subnet mask

Manual Dotted Decimal to Binary Conversion
- best way to convert is with a calculator
- start with 128 and divide the number in half all the way to 1
- the place the binary numbers under the values from dividing 
- then add the decimal values that have a one underneath
-  128  64  32  16  8  4  2  1
   1      0    0     1   0  1  1  0
   128 + 16 + 4 + 2 = 150











  

 

Chapter 7: TCP/IP Basics Pg 184 - 198

IP Addresses
- most common IP addresses have a 32-bit value (IPv4)
- 32 binary digits broken into four groups of eight digits
- each 8bit value is converted into a decimal number between 0 and 255

Network IDs
- each computer on a LAN has a very similar IP address
- i.e. only the last number of the IP being unique to each system

Interconnecting
- must have a router to connect to other networks

Network+ Chapter 7: TCP/IP Basics pg 177 - 183

The TCP/IP Protocol Suite
- TCP/IP Model: Link, Internet, Transport, and Application layers

Internet Layer Protocols
- takes data chunks from the transport layer, adds an address, and creates the final IP packet
- IP then hands the IP packet to layer 2 for encapsulation into a frame
- ICMP: Internet Control Message Protocol
- full IP packet has 14 different fields

• Version (Ver): defines the type of IP address
• Header Length: total size of the IP portion of the packet in words
• Differentiated Services code Point (DSCP): contains data used by bandwidth sensitive applications 
• Time to Live (TTL): prevents an IP packet from indefinitely spinning through the internet 
• Protocol: Either TCP or UDP 

Transport Layer Protocols
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)

TCP
- 95% of all TCP/IP applications use TCP
- requires both the sending and the receiving machines to acknowledge the other's presence and readiness to send and receive data
- ACK/NACK or just ACK
- chops up data into segments, gives the segments a sequencing number, and verifies that all segments were received
- each application is designed a specific port number
- web servers use port 80 (HTTP)
- e-mail uses port 110 (POP3)
- TCP Headers

• Sequence Number: used to assemble/disassemble data
• ACK Number: tracks the readiness of the two communicating systems 
• Flags: give sending an receiving ends detailed information on state of connection
• Checksum: checks the TCP header for errors
• Source Port
• Destination Port 

 - UDP works best when transferring large amounts of data
 

Chapter 6: Installing a Physical Network pg 170 - End

Cable Testing
- need a midrange tester with TDR
- include the patch cables

Problems in the Telecommunications Room
- keep your diagnostics process documented and organized
- all racks should run off of an interruptible power supply
- all rooms should have temperature monitors
- all rooms should have environmental monitors

Things To Remember From Chapter:

1. Coax cable should not be used in structured cabling networks.
2. Bonding, or link aggregation, is the process of using multiple NICs as a single connection, thus increasing speed.
3. The CAT 5e rating requires four pairs of wires.
4. The patch panel organizes and protects the horizontal cabling in the telecommunications room. 
5. Patch cables are used to connect the hub to the patch panel and the PCs to the outlet boxes.
6. 10BaseT and 100BaseT use UTP cabling in a star topology. 10Base2 is an older, dying technology that doesn't use UTP in a star. Fiber-optic networking uses a star topology, but the name is a dead giveaway hat it doesn't use UTP. 
7. A tone generator and tone probe work together to enable you to pick a single cable out of a stack of cables.

The Beginnings of How the Internet Works

So I began the learning process first my replicating the demonstration in the presentation. The idea is to visualize and understand how one machine connects to another. I chose to see the connection between the machine here at the career center and python.org. I began by installing Scapy, and Graph Visualization Tools. I opened Scapy and use the traceroute command to see a list of all the IPs that my machine connects to in order to connect to python.org. I then used a command that would create an visual graph of all the hops the request took to reach python.org

Net+ Chapter 6: Installing a Physical Network pg 133 - 169

Patch Panels and Cables
- patch panel
        - a bow with a row of female connectors in front and permanent connections in the back
- 110 Block
        - UTP cables connect using a punch down tool
- 66 Block
        - used more commonly for telephone services but still common to find 66-blocks in a telecommunications room
- patch panels prevent horizontal cabling from being moved
- patch panels are also used to organize cables
- patch panels are available in:
        - UTP
        - STP
        - Fiber Optic
        - a mix of the three standards
- UTP patch panels come with ratings
- patch cables:
        - short (2-5 foot) UTP cables
        - stranded core

Demarc
- physical location of the connection and marks the dividing line of responsibility for the functioning of the network
- NIU:
          -> DSL or cable modem supplied by your ISP

Installing Structured Cabling 
- get a floor plan
- map the runs of the cables
- find an appropriate room for telecommunications
         - short distances from work areas
         - has a lot of power sockets
         - low humidity
         - temperature controls
         - not easily accessed

4th Quarter

1. During the 4th quarter, I will learn to properly set up and manage a school tool server for use in Senegal. In addition, I will complete a Python task that is essentially what this woman did.

2. During the 4th quarter, I will make a server for students in Senegal to use. I will also work together with Ben and John to complete a project on understanding how the internet works.

3. I hope to have tested and completed certification in Network+ by May 16th.