Intro to Troubleshooting- Week 6 Flashcards
ICMP
internet control message protocol- mainly used by a router or remote host to communicate why a transmission has failed back to the original host
ICMP type
8 bits, specifies what type of message is being sent
ICMP code
indicates a more specific reason for the message`
ICMP checksum
like all the other checksums
ICMP rest of header
optionally used by some of the specific types and codes to send more data
ICMP data payload
contains the entire IP header and the first 8 bytes of the data payload section of the offending packet
PING
a special type of ICMP
PING echo request
used to determine the state of a connection
The ping utility sends what message type?
an echo request ICMP message type
traceroute
lets you discover paths between 2 nodes and gives you info about each hop along the way
what does traceroute on linux and mac send?
UDP packets to very high port numbers
tracert
traceroute on windows- sends an ICMP echo request
mtr
long-running traceroute on linux and mac
pathping
long-running traceroute on Microsoft
nc
netcat- mac and linux- tests port connectivity
what are the arguments for nc?
nc + a host + a port
what will nc -v -z +x +x tell you?
if a connection to a port is possible or not
which text command tells you the IP address for a host name?
nslookup + hostname
which text command do you enter if you want to know the name resolutions for a server instead of the default server name?
nslookup [enter]
> [server + address of server]
which text command do you enter if you want to know the record name, other than the A record, for a host?
nslookup [enter]
> [set type= MX +hostname] (or AAAA, or text)
which text command do you enter if you want to know information about the packet sent to the server and the resulting answer.
nslookup [enter]
>[set debug + hostname]
What IPs does google’s public IP run on?
8.8.8.8 and 8.8.4.4
How are public servers useful for troubleshooting?
you can test general internet connectivity by sending a ping request to one.
what IPs does level 3 comm’s public domain use?
4.2.2.1- 4.2.2.6
registrar
an organization that’s responsible for assigning individual domain names to other organizations or individuals
host file
a flat file that contains, on each line, a network address followed by the host name it can be referred to as
What is the loopback address for IPv4?
127.0.0.1
What does sending traffic to the loopback address do?
Sending traffic to a loop back address bypasses all network infrastructure itself and traffic like that never leaves the node.
Why should host files no longer be used today?
are a popular way for computer viruses to disrupt and redirect users’ traffic.
PaaS
Platform as a service- the most common platform. gives programmers all the tools they need to deploy, administer and maintain a Web application.
SaaS
software as a service. a way of licensing the use of software to others while keeping that software centrally hosted and managed.
IaaS
infrastructure as a service. abstracts away the physical infrastructure. client responsible for everything else.
what are the requirements for virtualization for a client’s physical machine?
hypervisor support, enough RAM for each VM, and storage space.
resource pooling
Any time you can consolidate systems’ physical and time resources
measured service
when you are charged based on the traffic that goes in and out of your Web application or for the time that every single one of your virtualized servers is running rather than a fixed monthly or yearly fee.
metered service
when you’re charged by the amount of processing resources used, such as CPU usage so you pay for what parts of the hardware you use, rather than a more general fee for all the hardware of a system.
