Must Review Flashcards
FTTN vs FTTP
Fiber to the Node - Goes to box in neighborhood, then coax line to house ethernet
Fiber to the Premises - fiber all the way, links to an optical network terminal in house (ONT)
Both provide Gbps speeds
802.11a
First standard to use 5GHz band, has good throughput.
Max 54Mbps with 150ft range, really gets more like 25Mbps
802.11b
Uses 2.4GHz band, first ubiquitous standard. 11Mbps lab, 4-6Mbps reality.
Max range 300 ft
802.11g
2.4GHz band, backwards compatible with b devices
Combines best of a and b
Speed of a (54MBps) with range of b (300 ft)
802.11n
“Wi-Fi 4”
Dual band, both 2.4 and 5 simultaneously
MIMO - Multiple in, multiple out for simultaneous connections (more than one antenna)
lab 600Mbps, reality 100+ mbps
WAPs use trasmit beamforming to optimize signal and reduce deadspots
802.11ac
“Wi-Fi 5”
5Ghz only, allows for dual banding but applies 802.11n for 2.4 GHz band
Maxes at 1+Gbps
802.11ax
“High Efficiency Wireless (HEW) or Wi-Fi 6/Wi-Fi 6e”
2.4 and 5, 6e adds 6GHz band
Labthroughput at 10Gb/s
RADIUS
Remote Authentication Dial-In User Service
Security measure for accessing wifi
Open standard, partially encrypted, uses UDP ports 1812 & 1813
TACACS+
Terminal Access Controller Access-Control System Plus
Cisco developed, but opened a version for public use, uses TCP port 49
Public vs Private IP
Public address is like your passport to the internet - used to direct all traffic to you., Public IP address is typically the router’s outward facing address
Private IP address is only for internal network - allows router to distinguish between the different hosts on the network.
Classes of private addresses:
10.0.0.0 - Class A
172.16.0.0 - 172.31.255.255 - Class B
192.168.0.0 - Class C
CIDR
Classless Inter-Domain Routing
Masks using the binary values and “whack” notation
11111111.11111111.11111111.00000000 = /24 network (whack 24).
Remaining 0s are open for host IDs, while 1s are taken up with network ID
link-local address
Automatically assigned to machine when it has not been manually configured or DHCP configured.
Valid only within the private network, routers will not transmit traffic using link-local addresses
IPv4 range: 169.254.0.0/16 (remember 169.254.0.0 and 169.254.255.255 are reserved)
IPv6 range: fe80::/10 (although typically get assigned within the fe80::/64 range)
TXT Records
Spam prevention tools, supposed to make spoofing more difficult
DKIM - Domain Keys Identified Mail
digitally signs mail with a key pulled from the DNS server’s TXT records
SPF - Sender Policy Framework
list of servers that are permitted to send mail from a particular domain
DMARC - Domain-based Message Authentication, Reporting, and Conformance
references DKIM and SPF frameworks, determines what to do with mail that fails these checks
ipconfig w/ switches
shows the network settings
ipconfig /all - detailed view
ipconfig /renew - get a new DHCP config
ipconfig /release - dump current DHCP config
nslookup/dig
Win/UNIX
gives details on what DNS is giving you
nslookup [address/domain]
APIPA
Automatic PRivate IP Addressing
IPv4 range of 169.254.0.1 - 169.254.255.254
Host broadcasts it out, if no other host responds, it self-assigns.
Network Troubleshooting Tools
(Physical tools, equipment, and command prompt)
ipconfig - check to see if you are getting an APIPA, that means connection issue with DHCP
check link lights - if they keep going on and off, could be a sign of “port flapping”
Loopback test - test internal NIC circuitry, may need loopback plug to check external port pins
TDR - (Time-domain reflectometer) sends signal that will refelect back if impedence changes, calculates distances to break. Should always include the patch cables in this test
Toner - tone generator and tone probe. Sends signal that the probe will pick up when placed next to cable (like current detector tool)
net
command prompt - view details of a network as well as other tools
net use x: \server1\research = go into server1, find the research folder, map it to drive X:
net view \[NAME] gives available shares and mappings of \[NAME]
DNS
Domain Name System - UDP - Port 53
DHCP
Dynamic Host Configuration Protocol - UDP - Port 67, 68
LDAP
Lightweight Directory Access Protocol (queries a database) - TCP - Port 389
SNMP
Simple Network Management Protocol (endpoint management) - UDP - Port 161, 162
Can gather insane amount of data if queried, remote configuration and monitoring
SMB/CIPS
Server Message Block/Converged Internet Protocol Service (folder/file sharing) - TCP port 445 - UDP port 137, 138, 139
NetBIOS/NetBT
UDP port 137, 138 - TCP port 139
HTTP/HTTPS
Hypertext Transfer Protocol/Hypertext Transfer Protocol Secure - port 80/port 443
FTP/SFTP
File Transfer Protocol/Secure File Transfer Protocol - port 20, 21/port 22
IMAP/POP3
Internet Message Access Protocol/Post Office Protocol - incoming email - port 143/port110
SMTP
Simple Mail Transfer Protocol - outgoing email - port 25
Telnet
Terminal emulation - port 23 (very insecure)
SSH
Secure Shell Protocol - encrypted terminal emulation - port 22
RDP
Remote Desktop Protocol - port 3389
Types of Remote Access
Telnet - should only use within own LAN, unprotected connection
SSH - encrypted tunnel, can also move files (called tunneling)
VNC - Virtual network computing
MSRA - Microsoft Remote Assistance (remote control)
chown
Change owner (chown [new owner] file name)
Change Owner and/or Group (chown [owner]:[new group] file name)
pwd
UNIX - full path
Get-[command]
WINDOWS - gives info on command
dir
dir /p
WINDOWS - shows directory contents
shows directory contents but pauses after one page
ls
ls | more
ls -l
UNIX - shows directory contents
shows contents but pasuses after one page
shows long form details on contents
cd \path
cd ..
changes directory focus
moves focus up a directory (to parent)
rmdir [name]
UNIX AND WINDOWS - remove directory
rd [name] /s
WINDOWS - remove directory and all contents
more [name]
WINDOWS - when in directory, writes out contents of txt file. Allows of pagination
rm -r [name]
UNIX - remove direcotry and alll contents
cat [name]
UNIX - when in directory, writes out contents of txt file
del [name]
WINDOWS - deletes a file
rm [name]
UNIX - deletes a file
cp [name]
UNIX - copy a file
mv [name]
UNIX - move a file
move [name]
WINDOWS - moves a file
xcopy switches
/s - copy all subdirectories that aren’t empty
/e - include all empty directories
Robocopy syntax and mirror switch
robocopy [source path] [destination path] [options]
/mir - mirror source structure
gpresult syntax
gpresult /user [username] /r
sfc
WINDOWS - system file check, fix corrupted files
ps aux
UNIX - onetime snapshot of current processes (detailed)
top
UNIX - focuses on resource hungry process
chkdsk /f /r
WINDOWS - scan, detect, and repair disk issues
/f - fix file errors
/r - locate and repair bad sectors
find syntax
UNIX:
find [path] -iname “criteria”
looks for files that match criteria
apt-get update
UNIX - Updates Ubuntu systems
nano
UNIX - creates a text file
nano “file” for name
dd
UNIX - create an image of a drive
df -h
UNIX - what diskspace is free?
-h switch creates human friendly output
USB Speeds
USB 1.1 - 12Mbps
USB 2.0 - 480Mbps
USB 3.0 - 5 Gbps
USB 3.1 - 10Gbps
USB 3.2 - 20Gbps
USB-C - 20 GB/s
Thunderbolt
40Gb/s, used for high resolution displays and charging
SATA Cables
SATA 1 - 1.5 Gbit/s, 150 MB/s
SATA II - 3 Gbit/s, 300 MB/s
SATA III - 6Gbit/s, 600 MB/s
