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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
The PDU at the Network layer is called?
The PDU at the Network layer is referred to as a packet. A PDU at the Data Link Layer is referred to as a frame.
What is the difference between IP4 and IP6?
IPv6 is based on IPv4, it is an evolution of IPv4. So many things that we find with IPv6 are familiar to us. The main differences are:
1.Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing.
Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.
2.Address extended to 128 bits. This allows for hierarchical structure of the address space and provides enough addresses for almost every 'grain of sand' on the earth. Important for security and new services/devices that will need multiple IP addresses and/or permanent connectivity.
3.A lot of the new IPv6 functionality is built into ICMPv6 such as Neighbor Discovery, Autoconfiguration, Multicast Listener Discovery, Path MTU Discovery.
4.Enhanced Security and QoS Features.
Answer:
IPv4 means Internet Protocol version 4, whereas IPv6 means Internet Protocol version 6.
IPv4 is 32 bits IP address that we use commonly, it can be 192.168.8.1, 10.3.4.5 or other 32 bits IP addresses. IPv4 can support up to 232 addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.
IPv6 is 128 bits, can support up to 2128 addresses to fulfill future needs with better security and network related features. Here are some examples of IPv6 address:
1050:0:0:0:5:600:300c:326b
ff06::c3
0:0:0:0:0:0:192.1.56.10
The most important difference is that it has a larger address space. IPv6 uses 128 bits, instead of the 32 bits used in an IPv4 address.
There are also some changes in the header format, and some additional options, like built-in security options. These can be added to IPv4 through additional protocols, so this is really no big deal.
IPv4 is like 10.36.05.2 while IPv6 is one huge garble.
IPv4 is a 32 bits IP address that we use commonly, it can be 192.168.8.1, 10.3.4.5 or other 32 bits IP addresses. IPv4 can support up to 232 addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.
IPv6 is 128 bits, can support up to 2128 addresses to fulfill future needs with better security and network related features.
Here are some examples of IPv6 address:
1050:0:0:0:5:600:300c:326b
ff06::c3
0:0:0:0:0:0:192.1.56.10
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The main difference, at least the one that is most relevant for a transition from version 4 to version 6, is the length of the addresses. IPv4 uses 4 bytes; IPv6 uses 16 bytes for the address.
Mainly, IPv6 has a larger addressing space; IPv6 addresses use 128 bits instead of 32 bits.
Bounded MediaB: Bounded media are the physical links through which signals are confined to narrow path. Bounded media are made up of a external conductor(usually copper) bounded by jacket material. These are also called guided media.
In computer networks based on the Internet Protocol Suite, a subnetwork, or subnet, is a portion of the network's computers and network devices that have a common, designated IP address routing prefix (cf. Classless Inter-Domain Routing, CIDR). A routing prefix is the sequence of leading bits of an IP address that precede the portion of the address used as host identifier (or rest field in early Internet terminology). In IPv4 installations, the routing prefix is often expressed as a "subnet mask", which is a bit mask covering the number of bits used in the prefix. It is frequently expressed in quad-dotted decimal representation, e.g., 255.255.255.0 is the subnet mask for the 192.168.1.0 network with a 24-bit routing prefix (192.168.1.0/24). Subnet masks in IPv4 do not have to have consecutive bits set, e.g., a subnet mask of "11111111001100110000000000000000" (binary) is permissible, albeit of little additional value, as it does not provide for more efficient address space utilization and cannot be represented in CIDR notation. IPv6 does not use subnet masks and such non-standard routing prefixes are not possible. The routing prefix of a subnet is often further divided into the network's network identifier and a subnet identifier. The network identifier is the leading set of address bits that is common to the prefixes of all subnets in the network. This would typically be the CIDR routing prefix of an organization's entire address space allocation. The subnet identifier consists of the remaining bits in a subnet's prefix after the network identifier. In the cited example, 192.168.0.0 is the network identifier (and 255.255.0.0 the network mask) and "1" is the subnet identifier. In a large organization's network, without subnetting, traffic levels can grow enough that excessive rates of Ethernet packet collisions become a bottle neck due to the nature of Ethernet (cf. carrier sense multiple access with collision detection). For this reason, subnetting can be used to break the network into smaller more efficient subnets. Such subnets can be arranged hierarchically, with the organization's network address space (see also Autonomous System) partitioned into a tree-like structure. Routers are used to manage traffic and constitute borders between subnets. Communication is of specific link-local character (Ethernet broadcast) only within the smallest subnet. A typical subnet is a physical network served by one router, for instance an Ethernet network (consisting of one or several Ethernet segments or local area networks, interconnected by network switches and network bridges) or a Virtual Local Area Network (VLAN). However, subnetting allows the network to be logically divided regardless of the physical layout of a network, since it is possible to divide a physical network into several subnets by configuring different host computers to use different routers. While improving network performance, subnetting increases routing complexity, since each locally connected subnet is typically represented by one row in the routing tables in each connected router. However, with intelligent design of the network, routes to collections of more distant subnets within the branches of a tree-hierarchy can be aggregated by single routes. Subnetting was originally introduced before the introduction of classful network addresses in IPv4 to allow a single larger network to have a number of smaller networks within it, controlled by several routers. Existing subnetting functionality in routers made the introduction of Classless Inter-Domain Routing seamless.
Can you edit saved conversations from MSN Messenger?
nope there is no possible way
Actually, this article (http://filetonic.com/blog/2009/09/15/recovering-msn-conversations/)
provides info on steps you can take to restore conversations.
How would you obtain the running configuration of a cisco 2600 router in priviledged mode?
In order to see the running configuration on a Cisco 2600 router, follow these steps from user executive mode.RouterName> Enable
RouterName# show run
dialog control
Why is it important that each computer on a network to have a unique name?
Think of it this way. If you had an identical twin and both of you are named exactly the same, how will people tell you apart?
Why do you need an application layer?
You don't unless you plan on networking or plan on using DSL to it's utmost. You can use DSL through the USB port but Ethernet, (network card) is more stable and slightly faster. The network card allows two or more computers to communicate with each other. Without it you cannot network.
Single
Why fiber-optic cable immune to electromagnetic interference?
Fiber-optic is transmitted using light so it is unaffected by electromagnetic intererence.
Can two computers have the same ip address in a local area network?
- Answer: No, two hosts/nodes on the same network, or subnet cannot share the same IP Address. This goes for everything with a NIC, or (network interface card), including IP Printers.
- Why?: Simply put, two hosts/nodes on the same network, or subnet cannot use the same logical addressing information. This would cause logical addressing errors during ARP, RARP, DHCP and DNS traffic (among many others), and prevent both machines from using the network at the same time, due to 'half of all packet transmissions' being sent, or received at any given point by one host/node, but never the other.
You cant find your password for your wireless router?
If you know you haven't changed the password from the original one (SHAME ON YOU) then it should be in the manual somewhere. If you DID change the password then the only way would be to Hard Reset the router. It puts everything back to the default settings and changes the password and log in name back also. You still need to know what the default names were. If you don't have the manual then go the company's web site and go to the support area and look for your model, it will tell you how to do all that and have a digital copy of your manual you can download.
Is it legal to connect to an unsecured network?
Provided they don't have a firewall to block you out of their network, yes. Anytime someone has a wireless network in their house, it extends farther than the house usually. You could theoretically drive coast to coast, and hardly ever loose a wireless network to tap into.
Also, If they have a security-enabled network, you will need to type in a password to get into the internet. Most people have a security-enabled network, because who wants someone else gettting on internet they are paying for? I have a security-enabled network. It works great! And you can see who is on your wirless router and you can kick them off any time!! That is what I like about secuity-enabled networks! Well, bottom line, you can get on someone else's internet, but you will be promted to type in a password, unless they have an unsecured network!
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A DNS address is the address to a server that converts a URL to an IP address. Most DNS address' are provided by your ISP, although there are many free DNS servers available.
What are the two ways to connect a cable modem to a PC?
A firewire or corssover cable can be used to connect any two computers that have these ports. However, a telephone modem can only be used to connect a computer to the internet.
OSI model does not cover all aspects of computer networks. So, it is not popular.
OSI model: it is a representation of what happens when 2 computers or nodes communicate with each other on a network.
Disadvantages of network security?
Disadvantages Of Cyber Security .
1. Improved hacker speed and ability.
2. Interconnected computers.
3. Improved viruses, malware and worms.
4. Increase in "cyberwarefare" possibly
5. More annomitty between hackers.
The Xerox company patented the Ethernet technology in 1975 listing not just one inventor, but actually 4 individuals as the inventors for Ethernet. These four individuals were Robert Metcalfe, David Boggs, Butler Lampson, and Chuck Thacker.
Which field are contained within an IEEE Ethernet frame header?
1)Source and destination MAC Address
2)FCS Field
Difference between transport and network layer?
+network layer logical communication between hosts
+transport layer: logical communication between processes
ex: we have 2 house and one house have 12 room. kids in the houses send letter together.
network layer: only send letter between the houses
transport layer: it make sure that the letter be sent to right the room in the house.
What is a protocol in computers?
"Protocol" is the set of instructions agreed upon by the communicating parties. Some examples are the following:
- FTP (file transfer protocol)
- HTTP (hypertext transfer protocol)
its basically the rules for exchanging information between computers or computer networks
What else do packets contains besides data?
Overhead. The packet header contains no useful data - at least, not useful for the end-user; it is of course very important to maintain the protocol functioning, for instance, the destination address is necessary in order to be able to send the packet to the correct destination.
Servers are basically computers dedicated to serving out files. They are required in order to distribute the information, without them you couldn't retrieve information. Websites and other online things are stored on servers which are then fed out to people who require these things. Servers are a vital thing for information sharing. Servers are also used in organisations as a central data point where files can be stored.
