Network+ Extra 11 Flashcards
___ (exterior gateway protocol) = uses hops
BGP
NAT : Inside local = A private IP address referencing an inside device
Inside global = A public IP address referencing an inside device
Outside local = A private IP address referencing an outside device
Outside global = A public IP address referencing an outside device
NAT
? the inside local addresses were automatically assigned an inside global address from a pool of available public addresses. This approach to NAT is referred to as ?. This is often referred to as “many-to-many,” as many inside local users (a network) are mapped to a pool of inside global addresses
Dynamic NAT (DNAT)
The protocol used between clients (for example, PCs) and routers to let routers know which of their interfaces have multicast receivers attached is IGMP.
IGMP
uses a source distribution tree, meaning that an optimal path is formed between the source router in a multicast network (that is, the router closest to the multicast sender) and each last-hop router (the router closest to each multicast receiver). However, before this optimal source distribution tree is formed, traffic from the multicast source is initially flooded throughout the entire network, Obviously, this initial flooding of multicast traffic causes traffic to be sent to routers not needing the multicast traffic, and it can unnecessarily consume bandwidth on the links between routers. After this initial flooding occurs, if a router interface receives the multicast traffic, and that traffic is not needed by the router (or if the traffic is needed by the router, but on a different interface), the router interface sends a prune message to its neighboring router, asking that it be pruned off of the source distribution tree, After the router interface sends these prune messages, the resulting source distribution tree (the path over which the multicast packets flow) is an optimal path between the source router and the last-hop route.
PIM-DM
uses a shared distribution tree. A shared distribution tree does not initially form an optimal path between a source router and each last-hop router. Instead, a multicast source sends traffic directly to another router, called a rendezvous point (RP). When another router in the multicast network wants to join the multicast distribution tree (because it received an IGMP join message from a client), that last-hop router sends a join message to the RP to join the shared distribution tree, as shown in Figure 6-20. The tree is called a shared distribution tree because all last-hop routers (routers with downstream multicast receivers) send join messages to the same RP, The benefit of ? is that the flood-and-prune behavior of ______ is avoided. However, by inspecting Figure 6-20, you might conclude that a drawback of ? is that a suboptimal distribution tree might be formed. Although that is initially true, after a last-hop router receives the first multicast packet from the multicast source, it can see the IP address of the multicast source. Then, based on its unicast routing table, a last-hop router can form an optimal distribution tree and then prune off the branch of the tree connecting it to the RP. This behavior is called shortest path tree (SPT) switchover.
PIM-SM
? is an administratively configured entry in a router’s routing table that specifies where traffic for all unknown networks should be sent.
default static route
To manage multiple APs, a company will use a wireless LAN controller (WLC) for centralized management and control of the APs.
WLC
Modulates data over an entire range of frequencies using a series of symbols called chips. A chip is shorter in duration than a bit, meaning that chips are transmitted at a higher rate than the actual data. These chips encode not only the data to be transmitted, but also what appears to be random data. Although both parties involved in a ? communication know which chips represent actual data and which chips do not, if a third party intercepted a ? transmission, it would be difficult for them to eavesdrop on the data because they would not easily know which chips represented valid bits. ? is more subject to environmental factors, as opposed to FHSS and OFDM, because of its use of an entire frequency spectrum.
Direct-sequence spread spectrum (DSSS)
Allows the participants in a communication to hop between predetermined frequencies. Security is enhanced because the participants can predict the next frequency to be used, but a third party cannot easily predict the next frequency. ? can also provision extra bandwidth by simultaneously using more than one frequency.
Frequency-hopping spread spectrum (FHSS)
