Error Messaging - ping

 ping Error Messages

Expired in transit

• Routing loop

Destination host unreachable

• No or bad default gateway
• Routing configuration error

No Reply

• Possible routing loop
• Host does not respond

Hardware - Protocols and the OSI Layers

 

OSI Layers

Layer 1 - Physical

• Transceiver
• Repeater
• Hub
• Media Converter
• Modem

Layer 2 - Data Link 

• NIC
• Bridge
• Switch 
• Wireless Access Point
• MAC Address (AKA Layer 2, hardware, & physical address)
• 802.3
• 802.11

Layer 3 - Network

• Router
• Layer 3 Switch
• IP
• IPSec
• ICMP
• IGMP

Layer 4 - Transport

• Multilayer switch
• Load balancer
• Firewalls
• IDS (Intrusion Detection System
• TCP
• UDP

Layer 5 - Session

• Establishes, maintains, & tears down the session

Layer 6 - Presentation

• Data formatting and data translation
• Encryption
• Compression
• IMAP
• JPEG
• MPEG
• SSH
• SSL

Layer 7 - Application

• Multilayer switch
• NGFW
• DNS
• FTP
• HTTP
• HTTPS
• SMTP

OSI Layers, Mnemonics, & How the data is packaged

 OSI (Open Systems Interconnection)

Here is how the OSI is laid out and how the data is packaged, The top 3 layers deal with data, the first layer where encapsulation takes place is Layer 4 (Transport) as it prepares to leave the system.

Traffic Analysis Tools - Part 2

 Network Flow and Data Analyzer

NetFlow - Cisco Product (Rebranded to IPFIX)

This tool collects all the packet metadata, not the entire packet.

A NetFlow exporter can be enabled on network devices such as switches, routers, and firewalls. 

It uses a NetFlow collector to aggregate flows from the exporters. 

Here are some of the items it collects:

• Source and destination MAC addresses

• Source and destination IP addresses

• Source and destination ports

• Packet and byte counts sent and received

• Timestamps

• TCP flags and encapsulated protocols

Traffic Analysis Tools - Part 1

 Throughput Testers

To test the performance of your network, you can transfer a large file between 2 PCs. Take the size of the data and divide it by the time it took for the transfer to complete. There are several online throughput calculators to help you.

The best way to test throughput on your network is to perform the test during the busy part of the day.

Here is a listing of a few throughput testers:

• iperf: iperf
• Ttcp: Ttcp
• bwping: bwping

Common Agreements: MOU, NDA, & SLA

 Common Agreements

MOU (Memorandum of Understanding)

Is a preliminary agreement to work together. An MOU is not contractually binding.

NDA (Non-Disclosure Agreement)

This is an agreement for protecting intellectual property (Proprietary information). Intellectual property includes software the company has developed. This may also include other items created by the company such as movies, music, and books.

SLA (Service Level Agreement)

An SLA will include performance expectations, measurable goals, guaranteed uptime, fines (monetary penalties) 

IPv4 versus IPv6 Differences

 IPv4 / IPv6

IPv4 - Public IP Address / Called Global Address in IPv6

IPv4 - Private IP Address / Called Unique Local Address in IPv6

IPv4 - APIPA (169.254.x.x) / Called Link Local in IPv6 (Begins fe80:)

Loopback: IPv4 127.0.0.1 / IPv6 - ::1/128 or ::1

Multicast: IPv4 first octet 224-239 / IPv6 ff00::/8

Subnetting problem for April 21st, 2024

 Subnetting Problen for 4/21/2024

We post daily subnetting problems for practice to prepare for the Network+ exam.

Feel free to post your answers in the comments section.

For this problem, we need the following (this is an IP address within the subnet, 185.68.68.113/26):

Network ID:

First Usable IP Address:

Last Usable IP Address:

Broadcast address: 

Port numbers you need to know for N10-008

 Network+ Port Numbers

This is a list of the port numbers and their associated protocols that you need to know for the exam:

20 TCP - FTP (File Transfer Protocol) - Data

21 TCP - FTP (File Transfer Protocol) - Control

22 TCP - SSH (Secure Shell), SCP (Secure Copy Protocol), SFTP (Secure File Transfer Protocol)

25 TCP - SMTP (Simple Mail Transfer Protocol) sends/relay email in plaintext

53 TCP/UDP - DNS (Domain Name System) Uses UDP for DNS queries, uses TCP for DNS zone transfers

67 UDP - DHCP (Dynamic Host Configuration Protocol) Server

68 UDP - DHCP (Dynamic Host Configuration Protocol) Client

69 UDP - TFTP (Trivial File Transfer Protocol) transfers files in plaintext

80 TCP - HTTP (Hypertext Transfer Protocol) Plaintext

110 TCP - POP (Post Office Protocol) Retrieve email in plaintext, email is no longer on the server

123 UDP - NTP (Network Time Protocol)

143 TCP - IMAP (Internet Message Access Protocol) Retrieve email in plaintext

161 UDP - SNMP (Simple Network Management Protocol)

162 UDP - SNMP (Simple Network Management Protocol - trap)

389 TCP - LDAP (Lightweight Directory Access Protocol) Plaintext

443 TCP - HTTPS (HTTP-Secure)

445 TCP - SMB (Server Message Block) File sharing

514 UDP - Syslog

554 TCP - RTSP (Real Time Streaming Protocol

587 TCP - SMTPS (SMTP - Secure)

636 TCP - LDAPS (LDAP - Secure)

993 TCP - IMAPS (IMAP - Secure)

995 TCP - POPS (POP - Secure)

1433 TCP - SQL (Microsft SQL server)

3306 TCP - MYSQL (Linux Database)

3389 TCP - RDP (Remote Desktop Protocol)

5060 TCP/UDP - SIP (Session Initiation Protocol) VoIP credentials

5061 TCP/UDP - SIPS (SIP -Secure)

Subnetting Problem for April 20th, 2024

 Subnetting Problem - 4/20/2024

We will add a daily subnetting problem. The answer to the subnetting problem of the day will be posted the following day.

Feel free to post your answers in the comments.

For this problem, we need the following (this is an IP address within the subnet, 187.49.75.43/27):

Network ID:

First Usable IP Address:

Last Usable IP Address:

Broadcast address: 

IPv4 IP Address Classes, Ranges, & Subnet Masks

 IPv4 Addresses

• Class D is for multicasting
• Class E is experimental

 

Default subnet masks

• Class A: 255.0.0.0 (/8)
• Class B: 255.255.0.0 (/16)
• Class C: 255.255.255.0 (/24)

 

RFC1918 Private IP Address Ranges

• 10.0.0.0 to 10.255.255.255 (Class A)
• 172.16.0.0 to 172.31.255.255 (Class B)
• 192.168.0.0 to 192.168.255.255 (Class C)

 

APIPA (Automatic Private IP Addressing)

169.254.0.0 to 169.254.255.255

 

Loopback

127.0.0.1 to 127.255.255.255

CIDR (Classless Inter-Domain Routing)

 CIDR, Subnet Mask, IPs, & Available

The /32 gives you one IP address and you can use that for an ACL (Access Control List)

Fiber Optic Networking Tool (OTDR)

 OTDR (Optical Time Domain Reflectometer)

Picture courtesy of Amazon

This tool is used to detect the location of a break in a fiber optic cable. The tool sends light pulses down the cable and determines how long the signal can bounce back from the break. The tool can verify that new splices are solid and will not cause any issues. 

SYSLOG Severity Level

 SYSLOG

CODE            LEVEL            DESCRIPTION

0                    Emergency        The system is unusable (kernel panic)

1                    Alert                   A fault requiring immediate                                                                          remediation has occurred

2                    Critical               A fault that will require immediate                                                                remediation is likely to develop

3                    Error                  A non-urgent fault has developed

4                    Warning             A non-urgent fault is likely to develop

5                    Notice                A state that could lead to an error                                                              condition has developed

6                    Informational     A normal but reportable event has                                                              occurred

7                     Debug              Verbose status conditions used during                                                        development and testing

Levels 0 through 4 are normally logged. Levels 5 through 7 are normally used during troubleshooting or testing.

SSID, BSSID, ESSID, & IBSS explained

 SSID, BSSID, ESSID, IBSS

SSID (Service Set Identifier)

The name of the access point that it is broadcasting (Beaconing)

Change it from the default SSID

Makes it easier to locate the correct AP (Access Point) in an area with multiple AP

BSSID (Basic Service Set Identifier)

This is the MAC address of the AP

The first 6 hexadecimal characters identify the manufacturer

The second 6 hexadecimal characters are the serial number

ESSID (Extended Service Set Identifier) 

Multiple SSIDs broadcasting the same name in an organization.

This is normally achieved through the use of a wireless controller

This makes it easier for employees as they move through a large office or building, that way they are still connected to the same SSID without any user intervention.

IBSS (Independent Basic Service Set)

This is using ad hoc topology, peer-to-peer

No access point is used to connect the devices

T568-A - T568-B Ethernet Wiring Standards

 T568-A vs T568-B

There are only 4 wires that change between the 2 standards. Use this math problem to remember:

1+2+3 = 6. Those are the only 4 wires that change, 1, 2, 3, & 6.

Hold the RJ-45 connector with the end towards you where the cable will be inserted. The locking tab should be facing the floor. 

T568-A begins White Green / Green

T568-B begins White Orange / Orange

With the green, orange, & brown colors, the striped one is before the solid. With the blue colors the solid blue is first.

Routing Protocols: Interior - Exterior

 Routing Protocols

INTERIOR ROUTING PROTOCOLS

• Used within a single autonomous system
• Uses private IP addresses

OSPF (Open Shortest Path First)

• Excellent for enterprise networks
• Uses a link-state algorithm
• Administrative Distance: 110
• Uses Dijkstra's algorithm

RIP (Routing Information Protocol)

• Small networks
• Distance Vector
• Slow convergence
• Not very scalable
• Administrative Distance: 120

EIGRP (Enhanced Interior Gateway Routing Protocol)

• Hybrid routing protocol (Advanced distance vector routing protocol)
• Administrative Distance: 90

EXTERIOR ROUTING PROTOCOL

• Used to communicate between different autonomous systems
• Used on the Internet

BGP (Border Gateway Protocol)

• Uses public IP addresses
• Administrative Distance: 20

Increasing Bandwidth to your Server

 Increasing Bandwidth

If you need or want to increase bandwidth to your servers, you will need to configure two things:

On the server, you will need to install a NIC with multiple ethernet ports and configure NIC teaming.

On the switch, you will need to configure LACP (Link Aggregation Control Protocol)

Network+ DNS Records to know for the exam

 DNS Records

RECORD         DESCRIPTION

A                      IPv4 address - Name to address

AAAA               IPv6 address - Name to address

CNAME           Canonical / Alias

MX                   Mail Exchanger

NS                   Name Server - Resolves names to IP addresses

PTR                 Pointer record - Resolves IP address to a name

SOA                 Start of Authority - Primary, serial number for version

SRV                 Service location - LDAP, Kerberos, Global Catalog

TTL                 Time to Live - How long a DNS is cached in seconds

TXT                 Text record - SPF & DKIM

CompTIA Network+ 802. Standards to know for the exam

 802. Standards

The following are the 802. standards you need to know for the exam:

802.1Q          VLAN tagging

802.1X          PNAC (Port-based Network Access Control) 

802.3            Ethernet

802.3af         PoE (Draws up to 15.4 watts)

802.3at         PoE+ (Draws up to 25 watts)

802.11          Wireless

802.11a        5GHz - 54 Mbps

802.11b        2.4GHz - 11 Mbps

802.11n        2.4 & 5 GHz - (Up to 600 Mbps) Wi-Fi 4

802.11ac      5 GHZ -  (Up to 1300 Mbps) Wi-Fi 5

802.11ax      2.4, 5, & 6 GHz (Up to 9600 Mbps) Wi-Fi 6

More data to be published on Wireless in a later post.

CompTIA's Troubleshooting Methodology for Network+

 Network+ Troubleshooting Methodology

Make sure you know the steps and their associated sub-steps.

1. Identify the problem:

• Gather information.
• Duplicate the problem, if possible.
• Question users.
• Identify symptoms.
• Determine if anything has changed.
• Approach multiple problems individually.

2. Establish a theory of probable cause:

• Question the obvious.
• Consider multiple approaches.
• Top-to-bottom/bottom-to-top OSI model.
• Divide and conquer.

3. Test the theory to determine the cause:

• Once the theory is confirmed, determine the next steps to resolve the problem.
• If the theory is not confirmed, reestablish a new theory or escalate.

4. Establish a plan of action to resolve the problem and identify potential effects.

5. Implement the solution or escalate as necessary.

6. Verify full system functionality, and if applicable, implement preventive measures.

7. Document findings, actions, and outcomes.

Routing Table Administrative Distance

 ADMINISTRATIVE DISTANCE

Environmental Issues for a Datacenter

 Environmental Issues

Temperature: High temperature makes it difficult for the cooling systems to operate efficiently. This can lead to system crashes or failures.

Humidity: High humidity leads to condensation which can cause corrosion and short circuits. Low humidity can lead to static charges which can damage electrical components.

Electrical: Systems need to have clean and stable power. Things that need to be protected against are blackouts, brownouts, surges, and spikes, all of which can damage a system. Battery backups, UPSs, and power distribution units will assist with clean consistent power.

Flooding: Floods can be caused by natural events such as storms, leaky plumbing, or even fire suppression systems. 

SFP, SFP+, QSFP, & QSFP+ Speeds

 Small Form Pluggable Speeds

SFP          1 Gbps

SFP+       10 Gbps

QSFP       4 x 1 Gbps for 4 Gbps

QSFP+     4 x 10 Gbps for 40 Gbps

Video 1. Intro to IPv4 Subnetting

 Introduction to IPv4 Subnetting

Video 2. IPv4 Converting Dotted Decimal to Binary

 Converting Dotted Decimal to Binary

Video 3. IPv4 Subnetting Rules

IPv4 Subnetting Rules 

Video 4. Basic Subnetting

 Basic Subnetting IPv4

Video 5. IPv4 Subnetting Problem

 IPv4 Subnetting Problem

CompTIA Network+ - IPv4 Subnetting Problems with Explanation

 IPv4 Subnetting Problems with Answers and Explanations

Introduction to Subnetting in the 3rd octet

 Intro to Subnetting in the 3rd Octet

IPv4 Subnetting in the 3rd Octet Part 2

 Subnetting in the 3rd octet Part 2

VLSM (Variable Length Subnet Masking)

 Variable Length Subnet Masking (VSLM)

Cable Connectors: Coax, Ethernet, Fiber

 Cabling Connectors

 

Phone / Modem

RJ-11

Ethernet

RJ-45

GG45

TERA

 

Coax

F Connector

BNC

 

Fiber

FC

LC - Local Connector

LC Duplex

MTRJ - Mechanical Transfer Registered Jack

SC - Subscriber Connector

ST - Straight Tip