what is proxy?
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Answer / azeem uddin
Definition: proxy: In communications, a proxy is something
that acts as a server, but when given requests from
clients, acts itself as a client to the real servers.
Analogy: Consider talking to somebody who speaks a foreign
language through a translator. You talk to the translator,
who receives your statements, then regenerates something
else completely to the other end. The translator serves as
your proxy. Key point: The communication terminates at the
proxy. In other words, the proxy doesn't forward data so
much as it tears it completely apart. For example, an HTTP
proxy doesn't forward every request sent through it.
Instead, it first examines if it already has the requested
web page in its cache. If so, then it returns that page
without sending another request to the destination server.
Because proxies completely terminate the communication
channel, they are considered a more secure firewall
technology than packet filters, because they dramatically
increase the isolation between the networks. Key point: You
will occasionally be scanned for proxies. ISPs scan their
users for proxies. Hackers scan the Internet looking for
proxies they can anonymize their connections with. Certain
servers (like IRC servers) scan clients for proxies in
order to prevent anonymous connections. Several websites
maintain lists of such
| Is This Answer Correct ? | 21 Yes | 1 No |
Answer / vadirajjr87
Its a server which helps to distribute ,monitor and control the flow of internet in a LAN.
| Is This Answer Correct ? | 6 Yes | 0 No |
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routing 1. Difference between RIPv1 and RIPv2? 2. How many number of routes carried by RIP packet? 3. Is OSPF link state or distance vector or path vector protocol? 4. What is the difference between OSPF and IS-IS and which one is preferred? 5. Can we use BGP instead of any IGP? 6. How many network types available in OSPF? 7. Different type of Link State Advertisements aka LSA? 8. LSA 3 and LSA 4 are generated by which router? 9. When to use Stub and Not So Stubby Area? 10. How to get the external routes without making area Not So Stubby? 11. What is the different type of route summarization available in OSPF? 12. What is the requirement of doing summarization? 13. A major network is advertised as summary in one area and few of the routes from that network is configured in another area. What will happen in that case? 14. If any of the OSPF area is not stabilized, does it impact another area? 15. What is the use of forwarding address in LSA 5 and LSA 7? 16. External routes are available in OSPF database but not installing in routing table? 17. If loopback is not configured, what will be the router- id selected by OSPF process? 18. Can we run multiple OSPF process in single router and what is the advantage of using it? 19. What are timers of OSPF? 20. Multicast address of used by OSPF. 21. OSPF works on which layer? 22. What is backbone area in OSPF? 23. Can we use OSPF without backbone area? 24. Is it required that OSPF router-id must reachable in IGP cloud? 25. After configuring new router-id, automatically it will be used or do we need to use some type of command to get it operational. 26. Why the secondary ip address of interface is not advertising in IGP cloud? 27. OSPF neighbourship is not coming up. Please tell the various steps to troubleshoot it. 28. One side MTU is 1500 and another side MTU is 1600. Does it affect neighbourship? 29. Provide process of DR and BDR election. 30. If DR is down and no BDR is configured what will happen? 31. What is the difference between a neighbor and adjacent neighbor? 32. My OSPF neighbourship is showing 2-way, what does it mean? 33. Define different type of OSPF neighbor states? 34. OSPF external routes are not redistributing? switching 1. Difference between hub, bridge and switch? 2. What is mac address and why it is required? 3. In layer 2 domain do we need ip address for communication? 4. What is arp and why it is required? 5. What is Spanning Tree Protocol aka STP? 6. What is the difference between STP, MSTP, PVST and RSTP? 7. Can we use the two same paths for same vlan? 8. What is the difference between broadcast and collision domain? 9. Define type of lan traffic. 10. What is destination address of broadcast frame? 11. Can we connect a switch to switch with straight cable? 12. Define functions of switch. 13. What is arp timeout? 14. What is aging process? 15. What is BPDU? 16. What is path cost? 17. Define selection criteria of STP root bridge. 18. How to non bridge decide which port will elect as root port? 19. If a nonroot bridge has two redundant ports with the same root path cost, how does the bridge choose which port will be the root port? 20. Port states of spanning tree protocol. 21. If the users face delay during initial login, what you will suggest to implement? 22. Why spanning tree BPDU filter is used? 23. Can I use BPDU filter on trunk ports? 24. What is port security? 25. I want to learn only a single mac from the port, what need to be configured? 26. Can we use spanning port-fast on trunk ports? 27. If management ip address is changed, will user’s traffic will be dropped? 28. Difference between trunk and access port? 29. What is UDLD and why it is required? 30. What is interface vlan on switch? bgp 1. BGP is IGP or EGP? 2. BGP is link state or distance vector protocol? 3. BGP uses which port? 4. When to use BGP? 5. Can I use BGP instead of any IGP? 6. Can I run two BGP process on single router? 7. What is Autonomous System? 8. Types of BGP routing table? 9. What is the BGP path selection criteria? 10. Define various BGP path attributes. 11. Why weight doesn’t fall under path attribute category? 12. What is confederation? 13. What is route reflector and why it is required? 14. What is no-synchronization rule? 15. Default BGP timers. 16. When does BGP use 0.0.0.0 router id? 17. Does route reflector come in actual path during traffic forwarding? 18. What is Site of origin aka SOO? 19. What is the cost of external and internal BGP routes? 20. Can we use local preference outside the autonomous system? 21. Does it require that BGP router-id should reachable in cloud? 22. What is recursive lookup in BGP and how it works? 23. What is the meaning of update source loopback? 24. If a static route is advertised in BGP without using update source what will be the next hop address in update? 25. Define various types of communities and why they are used? 26. If BGP neighbor state is showing idle what does it mean? 27. In Multihoming scenario if primary link gets fail, after how long traffic will be shifted to secondary link. 28. I am having two routes for remote destination but only single route is installing in routing table, what’s the reason for this? 29. How many links can be assigned for load balancing or sharing? 30. In eBGP I am establishing my neighbourship with loopback address but it’s not coming up. Please specify different reasons for not coming up. 31. Can we redistribute BGP in IGP? Please explain your answers. 32. What is cluster id? 33. I am receiving updates from eBGP peer, will the next hop change or not? 34. I am receiving updates from iBGP peer, will the next hop change or not? 35. A router is receiving same route from two different eBGP peers. The AS information contains in peer 1 is {65500, 65550, 65555} and in peer 2 is {65501, 65501}. But I want to make peer 1 preferred. 36. What is the difference between next-hop-self and update source loopback? 37. Define loop prevention mechanism in BGP. mpls and vpn 1. What is the difference between VPN and MPLS? 2. What is MPLS and why it is being so popular in short time? 3. What is the protocol used by MPLS? 4. MPLS works on which layer? 5. What is the difference between P and PE router? 6. Can I make my PE router as P? 7. Two routers are having 4 equal cost links, how many ldp sessions will be established? 8. My LDP router id, OSPF router id and BGP router id is different, will it work to forward the traffic of customers or not? 9. What is Penultimate Hop Popping and why it is required? Which router performs the PHP function? 10. I am receiving aggregate label, what does it mean? 11. What are the different types of labels? 12. How to make customer route unique? 13. What is the difference between RD and RT? 14. Can I assign a same RD to two different customers? 15. Is RD travels in route update? 16. My customer is having three branches and all are attached to three different PEs, In this case can I use the different vrf names? 17. What is downstream on demand? 18. How to filter MPLS labels? 19. What is the default range of MPLS labels in Cisco routers ? How to extend that range? 20. Without route reflector can I implement MPLS? 21. What is the difference between VPNv4 and IPv4 address family? 22. What is MP-iBGP? Can we use normal BGP in lieu of MP- iBGP? 23. What is LIB, LFIB? 24. What is CEF and without enabling CEF, can we make MPLS work? 25. I am receiving end to end customer routes on various PE but not able to ping those routes, what’s could be the problem? 26. What is explicit null and implicit null? 27. Default timers of LDP? 28. Does LDP require OSPF, IS-IS or BGP? 29. In neighbor discovery command, I am receiving only xmit, what does it mean? 30. What is transport address? 31. What is the RFC of MPLS? 32. Why MPLS is called multi protocol? 33. What is the difference between MPLS, SSL and IPSec? 34. I am using different vendor products and want to implement TDP, what type of challenges will you face? 35. Does MPLS support IPv6? 36. Can I use the existing IPv4 MPLS backbone for IPv6? 37. Define various troubleshooting commands in MPLS? 38. What is forward equivalence class aka FEC? 39. What is adjacency table? 40. Difference between MPLS IP and MPLS Label Protocol LDP command? 41. If MPLS get disable, will it harm my IGP or IPv4 traffic?
how does the user connectivity of network?
6 Answers HCL, Paricharya IT Solutions,
SNMP 
