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Which part of an ip packet does the router use to make routing decisions?
Wiki User
∙ 10y ago
the network portion of the destination ip address
Wiki User
∙ 13y ago
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Which table does a router use to make decisions about the interface through which a data packet is to be sent?
Routing table
What decisions do routers make as a packet enters an interface?
It determines which local IP on a given Router Table, be it DHCP or static, that packet is assigned to.
Do you have to hook the router up to a computer?
No - a router can connect to a computer, another router, a switch, a hub, a bridge or a modem. If you are connecting to the Internet via DSL or cable company you will need a modem/router to connect to them. You then attach your computer (or computers) to that router. Routers are useful because they make decisions about which way a packet of data goes - this network or this network? If you have one network that doesn't go anywhere (connect to the Internet or another network) a router is of no use to you and a switch generally does wonderfully and is cheaper than a router.
When would you use a router on an Ethernet network?
to split the Internet between different computers or to make it wireless if it is a wireless router
Where can one find more information about router addresses?
One can find information about their router address by reading the information in the router package that they buy. When buying a router one will need to make sure they are buying one big enough for their needs.
Which table does a router use to make decisions about the interface through which a data packet is to be sent?
Routing table
What portion of the IP packet does a router use to make forwarding decisions?
buffer
What decisions do routers make as a packet enters an interface?
It determines which local IP on a given Router Table, be it DHCP or static, that packet is assigned to.
What is default routing?
A router is a device that decides where to send a data packet in order to get it one step closer to its destination, and then sends it there.In order to make this decision, the router looks at the destination address on the packet and then consults a list of rules programmed into the router by the person who set it up.If there is no explicit rule covering this packet - if the router hasn't been programmed with a rule on how to route packets to this particular destination - then the router send the packet to the default route.In other words, the default route is the destination that a packet is sent to if the router doesn't have instructions to send it somewhere else.As an example, consider a simple home router that connects your home network to the Internet. This router will have two routing rules - one for computers on your internal network, and a default route. The default route will send packets upstream to your ISP. So any packet that's not going to another computer at your house will always be sent out to the Internet.HTH,Gdunge
What is packet forwarding?
Packet forwarding in simple terms is the forwarding of packets from one node to another from networking point of view. For example, a router or a switch. These networking devices make routing devices with the help of their routing tables and then select an outgoing interface. After that they make some changes in the packet header and push (forward) the packet to the selected interface. In case you don't know the meaning of packet. Packer is the smallest unit of size in networking. Different networks has different packet size. For example, in ATM Networks the packet size is of 53 Bytes.
What a router can do?
A router can do lots of things. One of its main purposes is to (a) maintain routing tables, and (b) resend IP packets it receives, according to these routing tables. In other words, it takes decisions where to send the IP packets. Therefore, it is routers that make the Internet (or smaller groups of interconnected networks, as in a medium-sized or large company) work.
What happens after the packet leaves the router?
After the packet leaves the router, it is sent to the receiving address that is contained in the header in its wrapper. It may not travel the same path as other packets that make up the message, however.
Describe 4 different scenarios when an ip router would drop packets that arrive on one of its interfaces?
1) ACL (Access Control List) policy instructs the router to drop it. This is a "rule" configured intentionally by the router's administrator to control traffic. 2) The packed fails an RPF (Reverse Path Forwarding) check. This is when a packet arrives with a source address that doesn't make sense, and it appears like an attempt at malicious activity. 3) The input queue is full. This is basically a symptom of the router being overloaded. 4) The packet fails a basic sanity check, such as TTL (Time to Live) expiring, or failing a CRC (Cyclic Redundancy Check), although that is actually a Layer 2 function, not IP. 5) The packet has a requirement that the router is unable to accomodate. Examples of this would be a non-UDP encapsulated IPSec packet whos destination address requires translation, or a multicast packet arriving at a router that is not configured for multicast routing.
How important is TTL to network security what is TTL for and can a Hacker use it to harm you PC or network?
TTL stands for "Time To Live". This is a piece of data in a network packet that specifies how many routers the packet can pass through before the packet expires and is thrown away. Every router that the packet travels through subtracts one from the TTL counter. When it reaches zero, the packet expires. The router will drop the packet, and then send a message back to the computer that sent the packet telling it that the packet has expired. The purpose of the TTL counter is to make routing loops less dangerous. Let me explain.... Routers are devices that look at an incoming data packet and decide where to send it to get it one step closer to its destination. It's possible for one or more routers to be configured such that router A sends the packet to router B, which sends it to router C, which sends it to router A, which then starts it over again. Without the TTL counter, this packet (and any subsequent packet sent to the same destination) would circulate endlessly, taking up bandwidth until someone fixes the routing loop. However, with TTL, each router subtracts one from the TTL counter until eventually the counter hits zero and the packet goes away, giving someone time to fix the problem before the links are so congested with looping packets that it's no longer possible to talk to the router. TTL can affect network security in a couple of ways. Most operating systems set the TTL counter to 64 or 128, which is a pretty large number that will guarantee your packet can get across the Internet. To improve your network security, you can set your TTL counter to a low number. If your internal network is only four routers wide, you can set your TTL to 4. This will ensure that any packets generated on your network will not travel very far beyond your internal network. An attacker can also use the TTL feature to probe your network for the existence and address of your routers. This feature is used by the "traceroute" or "tracert" utility. It works by sending out a packet with a TTL of 1. The first router that the packet encounters will decrement the TTL to 0, drop the packet, then send a message to the traceroute program telling it that the packet expired. By looking at the source address of this packet, traceroute knows the address of the first router. Next traceroute sends a packet with a TTL of 2, which causes the packet to expire at the second router, which sends a message back to traceroute and exposing its address. And so on. Once an attacker knows the addresses of your routers, he or she can start working on compromising them, which can cause you no end of security problems. The solution is to prevent these packets from reaching your routers by using a firewall to block them. HTH, Gdunge
What is routing protocle?
The routing protocol also specifies how routers in a network share information with each other and report changes. The routing protocol enables a network to make dynamic adjustments to its conditions, so routing decisions do not have to be predetermined and static.
Why use a router instead of a switch?
A router can route data to the correct network in a way that is similar to a switch's method. However, a router can also forward a message to its correct destination over the most efficient available route, to destinations far removed from the LANs to which it is connected. Switches and bridges use MAC addresses to make decisions, but for TCP/IP, routers us IP addresses to determine the path by which tp send a packet.
Do you have to hook the router up to a computer?
No - a router can connect to a computer, another router, a switch, a hub, a bridge or a modem. If you are connecting to the Internet via DSL or cable company you will need a modem/router to connect to them. You then attach your computer (or computers) to that router. Routers are useful because they make decisions about which way a packet of data goes - this network or this network? If you have one network that doesn't go anywhere (connect to the Internet or another network) a router is of no use to you and a switch generally does wonderfully and is cheaper than a router.
