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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
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.
Explain the Distance Vector Routing Protocols and its features?
Distance Vector means that Routers are advertised as vector of distance and direction. 'Direction' is represented by next hop address and exit interface, whereas 'Distance' uses metrics such as hop count.
Routers using distance vector protocol do not have knowledge of the entire path to a destination. Instead DV uses two methods:
- Direction in which or interface to which a packet should be forwarded.
- Distance from its destination.
I would suggest to start with CCIE R&S. This will provide you a rock-solid foundation for any of your future endeavors. After the R&S I think you need to study the market and see where the Cisco products are being used mostly. It doesn't make sense to do CCIE in Data Storage when Cisco has only a niche market share. I would suggest think about doing Wireless (WiFi is the future, period.) If you want fancy stuff, and plan to move into consumer market, then go for Voice or Security. Either way, go for R&S first, and then for any other track. Plus, Double-CCIE sounds manly and macho ;)
What does a client do when it has UDP datagrams to send?
When a client wishes to send a UDP datagram there is nothing that they are required to except to send it. The datagram will use a checksum to verify the integrity of the datagram and deliver it where it needs to go.
What are the routing metrics for OSPF?
OSPF uses cost as its routing metric .
cost is calculated for every outgoing interface of a router through which packets transfer.
it is calculated by the formula
cost = 100000000/(bandwidth of output interface)
most likely bandwidth of serial int is 1544kb= 1544000 bytes
PS: all cost calculation to be done in bytes for ease
What is deference between HTTP and HTTPS?
The "s" at the end represents a secure sever connection. They're usually utilized when making an online purchase, or logging into an account with sensitive information (i.e. online banking, loan repayment websites, etc)/
Transport layer three-way handshake?
for establishing connection between the end systems
here we have 3 steps
sender receiver
sync bit ==1
1................................................>>>>
reply to sync bit + sync bit of receiver
2. <<<< .................................................
replay to R sync bit
3. ....................................................>>>>>
whole process is in three steps so we call it as three way handshake
Which command turns on a router interface?
While in the interface mode your prompt should look like this:RouterName(config-if)#
Then type the command:
RouterName(config-if)# no shutdown
one number of host bits must be left when you doing subnetting.
Which two statements are true about the use of the debug ip rip command on a Cisco router?
The debug ip rip command displays RIP routing activity in real time.
The debug ip rip command can be issued at the user EXEC configuration mode.
Jh
What is the effect of command copy running config tftp?
This command will copy the running configuration (located in RAM) of a Cisco device to a TFTP server. After executing the command you will be prompted for further information about the TFTP server (Server Address, file name, etc.).
What is the Operational Definition of Telephony Quality of Service?
Quality of Service (QoS) is primarily applied to Internet telephony (IP telephony, VoIP).
In VoIP (Voice over Internet Protocol) telephony the cable frequently shared with internet connection.
If internet connection uses/occupies too much of cable's transmission capability by downloading or uploading files, there will be not enough cables resources to transmit telephony signal effectively thus making conversation impossible or with low hearing rate.
QoS reserves certain amount of cable's capability only for telephony, thus no matter how much internet connection is used, there is always enough room for plenty of simultaneous telephone conversations.
What commands can be used to verify that inter-VLAN communications is functioning?
Using a simple show command will suffice to view that vlan's are configured properly. If the vlan's are configured properly on the routers as well as the switches, then the routers can talk to each other and so can the vlan's.
show ip route - Provides a snapshot of the routing table entries.
ping - verifies connectivity
