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Cisco
Cisco Systems, Inc. is a major IT company, which produces networking equipment and network management solutions for both personal and commercial use. Questions about this company and its products belong here.
1,095 Questions
Ccna secuirty required ccnp router and switch?
Yes of course, CCNA Security required CCNP Router and Switching. CCNA Router and Switching cover the basic topic of networking starting from OSI Model, IP Addressing, router basic, RIP, EIGRP, VLAN, VTP, and many more and you must know basics before doing CCNA Security.
Which layer encapsulates the segments into packets?
TRANSPORT LAYER
The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.
The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagrams, the transport protocol should include extensive error detection and recovery.
The transport layer provides:
- Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
- Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
- Message traffic control: tells the transmitting station to "back-off" when no message buffers are available.
- Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).
Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, prepending a header to each frame.
The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.
Network Layer
At what layer in the osi model would you find protocols such as rip and ospf?
OSPF and RIP are used in the network layer of the ISO model.
What are some issues with physical isolation of a LAN from the rest of a network?
Well, there is no interaction from the outside world. No file sharing, Etc.etc. Imaging you disconnected your computer from the internet. Your limited to what the machine in your isolated lan has to offer.
It will use type 7 encryption and will encrypt only the privileged EXEC level passwords
Is cisco a good company from which to purchase business telephones?
"When speaking with a customer service representative for Cisco, ask for referrals to help with your question. Many companies offer testimonials from current and past customers."
What is the router static routes cisco 6.8.1?
for R1-ISP
network - 192.168.23.0
mask - 255.255.255.192
next hop - 192.168.23.121 (R2's S/0/0/0 IP Address)
for R2-Central
network - 0.0.0.0
mask - 0.0.0.0
next hop - 192.168.23.122 (R1's S/0/0/0 IP Address)
Your R2-Central is right but your R1-ISP is wrong Sir!
correct R1-ISP
network - 172.16.0.0
mask - 255.255.254.0
next hop - 172.16.3.97
Are frames in the network layer?
No. Frames are used on the data-link (layer 2) layer. Packets are used at the Network (layer 3) layer.
How do you make an invisible program?
To make a program invisible, you can take one of the following methods:
(1) hide the user interface of the program. most programming languages provide APIs (Application Programming Interface) for you to hide the windows, task bar icons and other visible elements.
(2) create your program as a service. Services don't need user interfaces, so they are invisible to normal users.
(3) inject your program into other hosts (programs). This is the typical behavior of Trojans and Virus, this kind of program is prone to be detected as malicious software by anti-virus software, so it is not a good method to create normal programs.
What would you recommend for the core switches?
Depending on the size of the network and actual traffic requirements technically a "core layer switch" can scale from a 2960 all the way up to and beyond a 6500.
Which two factors are important when deciding which interior gateway routing protocol to use?
We use igrp in a autonomous system
and we use eigrp between two autonomous systems.
show flash
Which Cisco IOS command assigns an ACL to an interface?
first get into the interface on which you want to apply the ACL and then assign the ACL using ip access-group command
syntax: ip access-group <ACL num/name> <in/out>
ex:-
int fa 0/0
ip access-group 10 in
Importance of Data communication?
Data communication plays a key role in daily productivity. As data holds a lot of information that companies need to fuction day-to-day, the communication of that data across the company is essential. People need to remain informed, and clear and effective data communication is the way to do that.
Difference between Straight cable and Cross Cable?
what is different between cross cabling and straight cabling ANSWER: a crossover cable is used to connect like devices, like a router to a router, but a straight through cable is used to connect dissimilar devices, like a router to a computer.
How is a virtual port connected and used?
Virtual Ports Virtual Ports are used in TCP and UDP to identify unique end-to-end connections. They are called 'virtual ports' because a single physical connector can serve multiple connections. Each side of a connection uses its own port number, which does not change during the life of that connection.
Client-Server PairingsAll TCP and UDP traffic utilizes a client-server scheme, so there is always a client port and a server port used for every connection.A pair of fields within the TCP and UDP headers is used to track the source and destination Virtual Port Numbers used for that socket connection. Each field in the header is sixteen bits wide, so the value in the field can range from 0 - 65534. Each computer host uses a unique IP address, and also uses a unique source and destination port pairings to identify that specific connection between the two computers. Typically, when your computer connects to a website, it connects to the destination website on port 80 (the default port for HTTP / web traffic). A different source port on the local host is used. At one time, this port number was the next number above 1024 that wasn't already in use for another connection. For example, the first website connection would be set up on the source port of 1025 and the second connection on 1026. If the 1025 port is no longer needed and is closed, and another port is needed, then 1025 would be used.
Today, to defeat hackers, computer systems are choosing the source port at random as hackers can predict this behavior and hijack sessions by predicting new connections being opened.
Servers run network services, these services are bound to a virtual port and listen for communication on that virtual port. It is possible for multiple clients to connect to the same service and thus, use the same destination port number when connecting to the server. Because each client uses a unique IP address and port number, the server can keep track of up to 65534 connections per host.
However, whether the port number is the source, or the destination port depends on which side is currently transmitting information. The client and server asynchronously transmit and receiving information using these ports.
What information in a frame does a switch or bridge use to populate the MAC address table?
Source MAC address and source port
What is 'err-disabled' error. it is frequently blocking the port of your cisco switch?
This is caused by port security being enabled and having the violation setting set to shutdown. This is triggered when you have two many MAC addresses listed for the port of if a BPDU is sent to that port, depending on how port security is configured.
