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URGENT REPLY SOUGHT_ FRAME.etc. issues!

Dear friends ,

Kindly give me authoritative answers to my following queries , since I am writing CCNA EXAM shortly:

1.When a download of frames/files takes place from a remote server on one's host PC then Frames landing at the host PC shall have WHOSE SOURCE MAC ADDRESS - THAT OF THE NEAREST ROUTER TO THE HOST PC OR THAT OF THE SENDER SERVER ?

2.A ROUTER AND A SWITCH ARE CONNECTED VIA FASTETHERNET PORTS - WHICH TYPE OF CABLING MUST BE USED - CROOSSOVER OR STRAIGHTTHROUGH (both fao ports use RJ 45 Connectors which means the same connecting devices on both ends- this creates confusion- if I am writing CCNA exam which option must I choose - CROSSOVER or STRAIGHTTHROUGH CABLE?)

3.A newly purchased router has old NVRAM in it , what must be done with this NAVRAM - SAVED OR ERASED ?

4.ARP really belongs to which OSI layer - Network or Datalink?

5.Are following correctly matched:

NTP- PORT 123( TCP)

NNTP - 119 (UDP)

6.What is the correct sequence to configure dial-on-demand routing on an ISDN BRI interface?

7.is it true that TE2 is a serial interface on a router? iF YES OR NO , REASONS FOR THE SAME.

8.Data field in a frame consists of 46-1500 bytes or 64-1500 bytes?

9.What is the basic function of frame-relay DLCI - is it identification of circuit between the local router and the nearest connecting Frame-Switch or the is it the identification of circuit between the far end router and the Frame-Switch?

9.Does multicasting not cause congestion?

10.Is it true that TRUNK PORTS are not configured on routers and that these are done so on switches only?

11.what is the maximum number of loopback interfaces that a router can have?

An early response shall highly be appreciated!

With Warm Regards

Lovely Person

2 REPLIES
Green

Re: URGENT REPLY SOUGHT_ FRAME.etc. issues!

The MAC of a recived frame will always be that of the last router. When a frame is received on "port a" of a router, the L2 frame is stripped and discarded. The router looks at the packet contained in the (discarded) frame and makes a routing decision. The router then re-encapsulates the packet in a new frame (with the transmission interface's MAC address) and sends it to the destination host on "port b".

A router connected to a switch will use a straight-through cable. Routers like PCs, are considered "end" systems. Cross-over cables are used to connect like-systems (PC-PC, Router-Router, switch-switch)

You should erase the NVRAM to clear the previous configuration so you can "start from scratch"

ARP is more of an L2 protocol than L3 (though it is not strictly in either layer). If you examine an ARP packet, you'll see that there's no IP (network) layer. ARPs are initiated as a local broadcast - since there is no L3 information, the ARP is restricted to it's broadcast domain.

NTP is UDP, NNTP is TCP (no, they're matched backwards)

DLCI is a layer two address. It's between the the local router and the Frame Switch. There will also be another DLCI between the far-end router and the switch, but it's not the same DLCI. DLCIs are "locally significant" they are only used for the specific like that they label.

Multicasting COULD cause congestion, but it generally thought of as a mechanism to reduce congestion. In a situation where 20 hosts are trying to view a six megabit video stream through a typical network, if all 20 used unicast, that would create 120 megabits of traffic. Using multicast, all 20 hosts "tune in" to the same multicast stream, using only six megabits.

10. True. Switches use (now, usually, 802.1q but older may use ISL) trunks. Routers use sub-interfaces that are enabled for 802.1q (or ISL) encapsulation.

You can have many / multiple loopbacks, but I don't remember the max number.

Good Luck on your test

Scott

Re: URGENT REPLY SOUGHT_ FRAME.etc. issues!

Hi Scott,

The max number is 2147483647

Regards,

Ankur

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