0
Computer Networking
Computer networks are collections of computers which are connected together in order to communicate and transfer information. Questions about computer networks, networking protocols, and how to set them up belong here.
18,810 Questions
What are three types of network profiles?
Local Profiles: profiles that are saved on a single computer. Users cannot access their profile from any other machine, regardless of whether the machine is attached to the network or not.
Mandatory Profiles: profiles that cannot be saved from one session to the next. A user may utilize any machine that is connected to the network. However, once a user logs off, any setting preferences made to the profile is permanently lost and must be reinstated at every log on. This ensures a profile will remain small and easy to manage, but renders users powerless from customizing their profile to their liking.
Roaming Profiles: do just what the name implies-they move around with you. If you log on to one computer today, and a different computer tomorrow, you're making use of a roaming profile to load your customized user settings. Roaming profiles are saved on the network so when you log on to any networked computer, your personalized desktop is loaded no matter what machine you're on. Users have full freedom of what's on their profile, which is convenient for them, but can lead to problems such as slow log on times and server crashes.
What is the purpose of caching in DNS?
When the web browser wants to load a web page, it needs to contact a DNS server first, which will translate the URL address into a machine readable format - the IP address. Even though the translation takes only a few hundred milliseconds each time a message is sent, these can add up over time, as the number of requests can easily reach hundreds or thousands of DNS queries. DNS servers can sometimes be unavailable and the responses to queries can be very slow.
To speed up this process is to cache the information locally thereby eliminating the need for repetitive queries to the remote DNS server. This is done by telling PostCast Server to contact a local database on your computer, rather than the remote DNS server. This local connection can be performed much faster and does not depend on the response time of the remote DNS server across the Internet.
PostCast Server contacts the remote DNS server once, and then caches (memorizes) the addresses returned from the query. So the next time you are requesting the same domain.com address, it instantly returns the answer, without having to contact your ISP's DNS server to ask it for the translation. The process is much faster, since it does not have to connect to any remote servers every time. Basically, the logic behind the DNS cache feature is to include both bad and good domains in the list and use the "Valid" column to mark them as valid. The domain is considered bad only if DNS server returns the "Unresolved" error, which means that the DNS entry for that domain does not exist.
How Computer network is similar to distributed network?
A computer network gives access to files on separate computer, while distributed computing is giving access to the CPU power of a separate computer
What part of the computer formats and presents data for people or other devices?
Any data sent to a output device formats the data and presents it to the user. There are many ways to present the data that a user can understand. Such as speakers are for sound and computer screens are for visual.
ya if they are on both side then.. if one side then not..
What are the steps in subnetting?
A service provider has given you the Class C network range 209.50.1.0. Your company must break
the network into 20 separate subnets.
Step 1) Determine the number of subnets and convert to binary
- In this example, the binary representation of 20 = 00010100.
Step 2) Reserve required bits in subnet mask and find incremental value
- The binary value of 20 subnets tells us that we need at least 5 network bits to satisfy this requirement
(since you cannot get the number 20 with any less than 5 bits -- 10100)
- Our original subnet mask is 255.255.255.0 (Class C subnet)
- The full binary representation of the subnet mask is as follows:
255.255.255.0 = 11111111.11111111.11111111.00000000
- We must "convert" 5 of the client bits (0) to network bits (1) in order to satisfy the requirements:
New Mask = 11111111.11111111.11111111.11111000
- If we convert the mask back to decimal, we now have the subnet mask that will be used on all the new
networks -- 255.255.255.248
- Our increment bit is the last possible network bit, converted back to a binary number:
New Mask = 11111111.11111111.11111111.1111(1)000 -- bit with the parenthesis is your increment
bit. If you convert this bit to a decimal number, it becomes the number "8‟
Step 3) Use increment to find network ranges
- Start with your given network address and add your increment to the subnetted octet:
209.50.1.0
209.50.1.8
209.50.1.16
...etc
- You can now fill in your end ranges, which is the last possible IP address before you start the next range
209.50.1.0 -- 209.50.1.7
209.50.1.8 -- 209.50.1.15
209.50.1.16 -- 209.50.1.23
...etc
- You can then assign these ranges to your networks! Remember the first and last address from each
range (network / broadcast IP) are unusable
MAN stands for mobile area network?
Metropolitan Area Network.
A network spanning an area the size of a city. It's not used very much though.
LAN and WAN are more common (MAN is between them in terms of size)
What is a Virtual private dial-up network?
A VPN or Virtual Private Network is a very popular business tool to enable company information to travel across the street or across the planet separate from anyone else's information and is unreadable by anyone between sender and receiver. Other people use VPNs for personal use but quickly find Police will notice the use of a VPN by a member of the public
What icon allows you to view networked computers when a network card is installed?
The 'Network' icon.
A VLAN is a virtual LAN. In technical terms, a VLAN is a broadcast domain created by switches. Normally, it is a router creating that broadcast domain. With VLANs, a switch can create the broadcast domain. This works by, you, the administrator, putting some switch ports in a VLAN other than 1, the default VLAN. All ports in a single VLAN are in a single broadcast domain.
Because switches can talk to each other, some ports on switch A can be in VLAN 10 and other ports on switch B can be in VLAN 10. Broadcasts between these devices will not be seen on any other port in any other VLAN, other than 10. However, these devices can all communicate because they are on the same VLAN. Without additional configuration, they would not be able to communicate with any other devices, not in their VLAN.
10base2 and 10base5 wires refers to?
10BASE2, or IEEE 802.3, is an early Ethernet Standard that makes use of industry-standard RG-58 coaxial communications cables connected to BNC T-connectors.
10BASE2 gets its identifier, assigned by the Institute of Electrical and Electronics engineers (IEEE), from the following characteristics: "10" means it has a maximum transmission speed of 10Mbps; "BASE" is shorthand for "Baseband Transmission" or "Baseband Ethernet," meaning that the medium only transmits Ethernet signals; and "2" refers to its maximum network segment length of 185 meters, rounded up to 200 meters.
there is the time it takes the source NICto place voltage pulses on the wire and the time it takes the receiving NIC to interpret these pulses. This is sometimes called NIC delay
Elementary data link protocols?
Elementary data link protocols must agree at the most rudimentary level. The data frame must be constructed from this level, and all protocols must agree.
What mechanism is used to achieve the separation between different vlans as they cross a trunk link?
VLAN tagging using 802.1Q protocol.
How does longitudinal parity works?
Longitudinal parity, sometime it is also called longitudinal redundancy check or horizontal parity, tries to solve the main weakness of simple parity.
The first step of this parity scheme involves grouping individual character together in a block, as fig given below 1.1fig.Each character (also called a row) in the block has its own parity bit. In addition, after a certain number of character are sent, a row of parity bits, or a block character check, is also sent. Each parity bit in this last row is a parity check for all the bits in the Colum above it. If one bit is altered in the Row 1, the parity bit at the end of row 1 signals an error. If two bits in Row 1 are flipped, the Row 1 parity check will not signal error, but two Colum parity checks will signal errors. By this way how longitudinal parity is able to detect more errors than simple parity.
Which one of the following is useful in debugging a program that communicates via a network?
Logic probe(not sure)
Which one of the following is a reason to use a hardware address?
To obtain a vendor code/serial number from the user.
Which access control model allows the owner of the resource to choose who can access the resource?
Discretionary access control
nswer Explanation: The discretionary access control (DAC) model permits the owner of a resource to identify the users who can access the resource. You become the owner of the resource by either creating the resource or by being granted ownership of that resource. You grant access to the resources using access control lists (ACLs).
