Interview Questions.

Question 1. What Is Routing?

Answer :

The ROUTING TABLE is a desk maintained inside the kernel that determines how packets are routed to different systems. A quantity of packages might also upload or delete routes from the routing tables, along with course, ifconfig, in.Routed and in.Rdisc. The routing table consists of three kinds of routes: HOST ROUTES are checked first and outline a direction to simply one host. NETWORK ROUTES are checked second and define a direction to all of the hosts on one community. DEFAULT ROUTES are used as a trap-all, while no host or network routes are located to a destination. They typically ship to a extra informed routing system, which has a better chance of being able to find a host or network route to the vacation spot.

Question 2. What Is Arp?

Answer :

P, the ADDRESS RESOLUTION PROTOCOL. ARP is the protocol which converts the IP cope with to an deal with appropriate to the hardware type (ie, Ethernet addresses on an ether community). After normal routing protocols have completed their paintings, ARP springs in to movement. It's what really gets packets from one system to every other. Usually, you have to no longer ought to worry about ARP at all. Except in unique setups, it must work absolutely transparently.

Networking Interview Questions
Question three. How Routing Starts Up?

Answer :

Solaris and SunOS each have a specific order which they use to start up routing: If an /etc/defaultrouter file exists, most effective static routing will be used, and a static default path can be created to the system indexed in the defaultrouter record. If there's no /and so forth/defaultrouter record, and the system is a router, each in.Routed and in.Rdisc may be started out, and they may put it up for sale routing statistics. SunOS machines will simplest begin up in.Routed, as in.Rdisc isn't available underneath SunOS. If there's no /and so on/defaultrouter document, and the gadget is a host, in.Rdisc is to begin with started out.

If any machines on the identical community market it through Routing Discovery, in.Rdisc might be used as the dynamic routing application if there aren't any machines advertising and marketing through Routing Discovery, in.Rdisc will speedy cease. SunOS skips this step. Finally, if there is no /and many others/defaultrouter record, and both the machine is walking SunOS, or in.Rdisc has failed, then in.Routed is commenced. It will concentrate for other in.Routed packages advertising thru RIP packets. This is the default way wherein maximum out-of-the-container Suns will perform.

Question 4. What Is Ip Addresses, Netmasks And Subnets?

Answer :

All IP ADDRESSES are divided into  quantities: the NETWORK ADDRESS, and the HOST ADDRESS. The network portion of the IP address defines the level at which routing is executed this means that all machines with the same community address are on the equal community. For example, if we had the IP address a.B.C.D, we would study that the community part of that deal with turned into a.B, and the host part of that deal with changed into c.D. In that case, all machines with the IP address a.B.*.* would be on the identical community. We would commonly see a route to the network a.B.Zero.0. By default, Internet IP addresses are divided into three Classes. Each of these levels has a distinctive part of the IP deal with reserved as the community and host addresses. Class IP Range Network Host 

Class A 1.*.*.* to 127.*.*.* a b.C.D 
Class B 128.*.*.* to 191.*.*.* a.B c.D 
Class C 192.*.*.* to 223.*.*.* a.B.C d 
Multicast: Class D 224.Zero.0.0 to 239.255.255.255. 
Reserved: Class E 240.0.Zero.Zero to 247.255.255.255

Networking Tutorial
Question five. What Is Ifconfig?

Answer :

It is usually satisfactory to start investigating routing issues by using making sure that your interfaces are installation efficaciously. By walking ifconfig, you can see your present day interface setup: # ifconfig -a lo0: flags=849<UP,LOOPBACK,RUNNING,MULTICAST> mtu 8232 inet 127.Zero.0.1 netmask ff000000 le0: flags=863<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST> mtu 1500 inet 150.One zero one.Sixteen.28 netmask ffffff00 broadcast one hundred fifty.One zero one.16.255 ether 8:zero:20:10:78:d When an interface is brought up, it routinely creates a direction.

This path can be to the nearby community for multipoint interfaces (ether, FDDI, TR, and so forth), or to a number for factor-to-point interfaces (PPP). If your essential interface (le0 in the above example) is not UP and RUNNING, truely no routing will be going on through it. If the interface is UP, you'll also want to have a look at the inet and netmask entries of your major interface, and ensure they are set correctly. If the inet is ready incorrect, take a look at your /and so forth/hostname.Interfacename record (ie, hostname.Le0) and your /and many others/hosts record. If the netmask is set incorrect, test your /etc/netmasks document

Network Security Interview Questions
Question 6. What Is Netstat?

Answer :

You can have a look at your modern-day routing tables via walking the command netstat, as follows: %%%% netstat -rn

Question 7. Explain Ping?

Answer :

If your trouble is not obvious from analyzing 'ifconfig -a' and 'netstat -rn', the ping command may be very useful in diagnosing it in addition. Try strolling 'ping -s gadget-with-no-course'. There are two opportunities. If you get a few sort of 'network unreachable' or 'host unreachable' error, this normally means that there's no path to your system to the device you are trying to ping. You will likely need to outline a static route for that machine's community, or possibly a default route. Following are a few examples. Under SunOS, you will just get the simple '... Unreachable' mistakes: %%%% ping -s lab-manta PING lab-manta: 56 records bytes sendto: Network is unreachable ping: wrote one hundred fifty.One hundred and one.89.28 sixty four chars, ret=-1 At this point, you need to go back to looking at your 'netstat -r' desk.

Network Security Tutorial Hardware and Networking Interview Questions
Question 8. What Is Traceroute?

Answer :

If you can't remedy your routing problems via searching at the routing tables and interfaces, a beneficial program for assisting clear up the hassle is traceroute. Solaris 2.7 software program bundles the popular traceroute software. Unfortunately, this program is not shipped with SunOS or Solaris earlier to 2.7, and as a result isn't always supported with the aid of SunService. However, you could easily discover a reproduction at the internet. The ftp web page ftp.Dfn.De includes traceroute beneath the /pub/tools directory. If you seek advice from 'archie' or other searching programs, it's far probable that you may be able to find a greater nearby reproduction. Traceroute works via sending out a hard and fast of three UDP packets.

These packets are initially given a Time-To-Live of one hop, that is then expanded to 2 hops, then to a few, and so on.... Till the packets attain the faraway gadget. This has the effect of stepping through the routers main closer to a vacation spot machine, one at a time. However, it additionally causes you to best see a unidirectional course, from your purchaser to the destination machines. It's quite feasible for routes to be different going from and to a machine, and traceroute will now not standardly show this. For example, if packets followed the following direction: --> C --> A B

Question nine. How To Set A Defaultrouter?

Answer :

If you need to define a default router, so you can send all of your non-local packets thru one standard device, simply create the file /etc/defaultrouter. It have to have as its sole contents, the hostname or ipnumber of your router: %%%% cat /and many others/defaultrouter router-1 or: one hundred fifty.A hundred and one.Sixteen.1 Note that any machine indexed as a defaultrouter _must_ be on the identical subnet as your system and the call listed in /and many others/hosts. On Solaris 2.4, and later, you could sincerely list multiple routers within the /and so forth/defaultrouter report, one default router consistent with line: %%%% cat /and so forth/defaultrouter router-1 router-2 router-three You also need to make certain that every call which seems in /and many others/defaultrouter has an access in your /and so forth/hosts record:

%%%% cat /and many others/hosts ... A hundred and fifty.One zero one.Sixteen.1 router-1 one hundred fifty.101.16.2 router-2 one hundred fifty.One hundred and one.16.3 router-three After you've got created /and so forth/defaultrouter, and made sure that any names indexed in that report also are listed in /and many others/hosts, you could reboot your machine. When it comes lower back up, it'll automatically be routing thru the defaultrouter that you have defined. If you have got a easy community, or in case you are simply trying to get routing to paintings after your Sun gadget is first installed, you probably want to installation a defaultrouter, as is defined here. Some similarly advice on what form of routing to apply. How does a couple of default routes work?

Switching Interview Questions
Question 10. How To Add Static Routes?

Answer :

At any time, you may add static routes in your system through the route command. The widespread syntax for adding a network direction is: direction upload internet "faraway-network-ip gateway-ip" 'hop-metric-count number' On Solaris 2.6: direction add -net "far off-community-ip gateway-ip" -netmask direction upload -host "host-ip local-intrf-ip" -interface faraway-community-ip is the community you're including a route to, gateway-ip is the ip cope with of the gateway that results in that remote-network. Hop-rely is an integer which identifies the quantity of gateways which you ought to undergo to get to the far off-network.

A community this is at once linked for your device could have a hop matter of zero (ie, the a hundred and fifty.One zero one.16.Zero net in the instance underneath). A far off-community this is immediately connected to a gateway-machine that is, in turn, on the same community as your system would have a hop count of one (ie, the a hundred and fifty.A hundred and one.17.Zero internet in the instance beneath). Static routes are hardly ever brought for far flung-networks with a hop be counted more than 1.

Question eleven. How To Use In.Rdisc?

Answer :

The in.Rdisc daemon is simplest available on Solaris gadget it relies upon on multicasting, which isn't present on older SunOS machines. If you do now not have an /and so on/defaultrouter document on a Solaris device, any routing host will automatically carry up in.Rdisc at boot time. As long as there is at the least one router on the identical network which advertises Router Discovery messages, in.Rdisc will continue running. If nothing responds to the preliminary Router Discovery queries, in.Rdisc on a routing host will mechanically stop, and the rc files will fall via to in.Routed. Solaris routers will even routinely convey up in.Rdisc at boot time, if there is no /and many others/defaultrouter document.

They will not ever exit, but instead will advertise via Router Discovery messages. If you need in.Rdisc to run, you should by no means should do something, other than delete the /and many others/defaultrouter record, if it exists, and make sure that as a minimum one Router Discovery compliant router exists on the equal subnet as your device. If you want to disable in.Rdisc, you must really rename it: %%%% mv /usr/sbin/in.Rdisc /usr/sbin/rdisc.Shop In fashionable, in.Rdisc need to simplest be run on routing hosts in case your nearby network is incredibly complex.

Network Administrator Interview Questions
Question 12. How To Use In.Routed?

Answer :

On a SunOS gadget, in.Routed will automatically be started out if there may be no /and so on/defaultrouter file and in.Rdisc didn't locate any Router Discovery compliant routers at the nearby network. In.Routed will mechanically start on routers if there may be no /etc/defaultrouter report, even if in.Rdisc is walking. In.Routed supports RIPv1 simplest.

You must now not want to do anything, aside from probable deleting an /and so on/defaultrouter record, in an effort to get in.Routed to run. You can pressure in.Routed to carry up wellknown community routes by way of placing entries for them into the document /and many others/gateways. The wellknown layout for that file is: net gateway metric passive or: net gateway metric lively far flung-community-ip, gateway-ip and hop-count.

Networking Interview Questions
Question 13. How To Force A Machine To Be A Router?

Answer :

If your system has as a minimum  interfaces in addition to lo0, or if your device has as a minimum one factor-to-factor interface, it's going to routinely be set up as a router. Solaris 2.X: The IP layer will generally act as a router (forwarding datagrams that are not addressed to it, among different matters) whilst the machine has two or more interfaces which might be up. This behavior may be overridden via using ndd(1M) to set the /dev/ip variable, ip_forwarding. The fee zero means do now not forward; the cost 1 approach forward.

Question 14. How To Force A Sunos Machine Not To Be A Router?

Answer :

If you do not want your a couple of-interface SunOS gadget to direction packets, you may want to rebuild the kernel. In the report /sys/netinet/in_proto.C, trade the following line: #define IPFORWARDING 0 to examine: #define IPFORWARDING -1 Afterwards, config the kernel, remake it, after which set up it. It may be useful to word, that on SunOS machines, IPFORWARDING may have three values: -1 Never forward IP packets zero Don't forward, however alternate IPFORWARDING to 1 if there are  or more interfaces 1 Always ahead IP packets

Question 15. How To Force A Solaris Machine Not To Be A Router?

Answer :

If you do no longer need your more than one-interface system, going for walks Solaris 2.Four or lower, to path packets, you just need to make a small trade to the file /and so on/init.D/inetinit. Find the subsequent two lines: numifs=`ifconfig -au grep inet wc -l` numptptifs=`ifconfig -au grep inet egrep -e '-->' wc -l` And at once after them, insert the following: numifs=2 numptptifs=0 After the system next reboots, it will now not act as a router.

If you are using Solaris 2.5 or more, it is even less difficult to make your device now not direction packets. Simply create an /and so forth/notrouter file: %% touch /and many others/notrouter Afterwards, reboot the system. It can be beneficial to be aware, that on Solaris machines, ip_forwarding will have 3 values: zero Never Forward 1 Always Forward 2 Only ahead whilst two or extra interfaces are up The above steps result in the ndd /dev/ip ip_forwarding variable being modified from "1" to "0", which prevents routing.

Cisco Nexus switches Interview Questions
Question 16. How To Set A Netmask Under Sunos?

Answer :

In order to include a everlasting netmask to your SunOS gadget, you should make an entry in the /and so forth/netmasks file, within the following format: network-address-with out-zeroes netmask For example: %%%% cat /and many others/netmasks a hundred and fifty.101 255.255.255.Zero The above could subnet the magnificence B community, one hundred fifty.One hundred and one.Zero.0, into 254 subnets, from 150.101.1.0 to a hundred and fifty.101.254.Zero. It is vital to notice that the entry in the left hand column need to be the authentic base network variety (ie # for a Class A, #.# for a Class B and #.#.# for a Class C), now not the subnet.

Question 17. How To Set A Netmask Under Solaris?

Answer :

In order to encompass a everlasting netmask to your Solaris gadget, you should make an access in the /etc/netmasks file, in the following format: community-address netmask For instance: %%%% cat /and so forth/netmasks a hundred and fifty.101.Zero.0 255.255.255.Zero The above would subnet the magnificence B community, a hundred and fifty.A hundred and one.Zero.0, into 254 subnets, from 150.One hundred and one.1.Zero to one hundred fifty.101.254.0. In 2.5.1 and below, only one access for the whole elegance network is authorized to guide general subnetting as specified in RFC-950 It is crucial to observe that the access within the left hand column have to be the authentic base community variety (ie #.Zero.Zero.0 for a Class A, #.#.Zero.0 for a Class B and #.#.#.0 for a Class C), no longer the subnet.

The 2.6 kernel has modified to guide VLSM. It is now possible to combine the RFC-950 and RFC-1519 shape of subnet mask inside the netmasks record. The community address ought to be the "SUBNETTED" cope with NOT the same old community wide variety based totally on the hosts ip cope with. (see guy web page for netmasks) Here are a few examples: A host address 192.188.206.65 with a netmask of 255.255.255.224 /and so forth/netmasks 192.188.206.64 255.255.255.224 A host deal with 172.31.Sixteen.193 with a netmask of 255.255.255.192 /and so forth/netmasks 172.31.Sixteen.192 255.255.255.192

Router Interview Questions
Question 18. How Does /ip Route Check-gateway Work?

Answer :

take a look at-gateway sends pings each 10 seconds. If  successive pings fail, the gateway is taken into consideration useless.

Network Security Interview Questions
Question 19. How To Filter Out The Default Route From Outgoing Bgp Advertisements?

Answer :

Assuming you've got a static default direction that is redistributed because redistribute-static parameter is about to sure, do the subsequent: 

/routing filter add chain=myfilter prefix=0.0.Zero.Zero/zero movement=discard

Then set myfilter as the out-filter for BGP example 

/routing bgp example set default out-filter=myfilter

Question 20. What Is Cdp?

Answer :

Cisco Discovery Protocol is a CISCO proprietary protocol to help administrators in amassing records approximately each regionally connected and remote gadgets. 

Multiprotocol Label Switching (MPLS) Interview Questions
Question 21. What Is Cost?

Answer :

Cost is the inverse percentage of bandwidth of the links. 

Question 22. What Is Hop Count?

Answer :

Hop count number is the variety of routers from the supply thru which facts should pass to attain the vacation spot community.

Question 23. What Is Bandwidth, Delay, Reliability, Load?

Answer :

Bandwidth - It is the Data capacity of a link in Kbps. 
Delay - It is the time takes to attain the destination. 
Reliability - The route with the least quantity of mistakes or downtime. 
Load - It is the amount of usage of a path. 
MTU - Maximum transmission unit (MTU) defines the maximum Layer three packet that can be sent over a medium. 
Network Troubleshooting Interview Questions
Question 24. What Is A Route Metric?

Answer :

Routing Protocol uses Route Metric cost to discover the quality path whilst there are two or extra one-of-a-kind routes to the equal destination. 

Different routing protocols use Route Metric to compute the gap to vacation spot. 

RIP - Hop Count, OSPF - Cost, EIGRP - Bandwidth, Delay, Reliability, Load, MTU. 

Hardware and Networking Interview Questions
Question 25. What Is Hybrid Routing Protocol?

Answer :

A Hybrid Routing protocol takes the advantages of each Distance Vector and Link State Routing protocols. 

It sends conventional Distance Vector updates. 
Lt has Link State characteristics additionally because of this it synchronizes routing tables among buddies at 
startup, and then it sends precise updates while community topology changes. 

Example:- Enhanced Interior Gateway Routing Protocol (EIGRP)

Question 26. What Is Link-kingdom Routing Protocol?

Answer :

Each router running a link kingdom routing protocol originates records approximately the router, its without delay connected hyperlinks, and the country of those hyperlinks. This facts is despatched to all the routers inside the community as multicast messages. 

Link-nation routing always try to maintain complete networks topology by updating itself incrementally handiest while network topology adjustments. Example:- Open Shortest Path First (OSPF) 

VLAN Interview Questions
Question 27. What Is Distance-vector Routing Protocol?

Answer :

Distance vector routing protocols use the distance or hops as metric to locate paths to destinations. 

Example:- Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP)

Switching Interview Questions
Question 28. What Are The Range Of Ad Values?

Answer :

zero to 255, wherein zero is the Best and 255 is the worst. 

Routing Protocol Administrative Distance Value 

Directly Connected zero 
Static path 1 
EIGRP ninety 
OSPF one hundred ten 
RIP one hundred twenty 

Question 29. What Is Administrative Distance (advert)?

Answer :

Administrative Distance is the trustworthiness of a routing protocol. Routers use AD cost to select the great route while there are  or more one of a kind routes to the equal vacation spot found out through  unique routing protocols.

Wireless Lan Interview Questions
Question 30. What Is An Autonomous System?

Answer :

An Autonomous System (AS) is a set of networks below a single administrative manipulate.

Question 31. What Is Egp?

Answer :

An Exterior Gateway Protocol refers to a routing protocol that handles routing between different 

Autonomous Systems (AS). Example:- Border Gateway Protocol (BGP).

Question 32. What Is Igp?

Answer :

An Interior Gateway Protocol refers to a routing protocol that handles routing inside a single self reliant machine. Example - RIP, IGRP, EIGRP, and OSPF. 

Question 33. What Is Routing Protocol?

Answer :

Routing Protocols learn the routes and provide the best routes from one community to some other community. 

Example - RIP (Routing Information Protocol) , EIGRP (Enhanced Interior Gateway Routing Protocol) and 

OSPF (Open Shortest Path First). 

Network Administrator Interview Questions
Question 34. What Is A Routed Protocol?

Answer :

A Routed Protocol incorporates facts from one community to another community. Routed Protocol contains user visitors 

which includes file transfers, net visitors, e-mails and so forth. 

Example:- IP (Internet Protocol), IPX (Internetwork Packet Exchange) and AppleTalk. 

Question 35. What Is A Dynamic Routing?

Answer :

In Dynamic routing, routes are learned by using using a routing protocol. Routing protocols will find out about routes from different neighboring routers going for walks the same routing protocol. Example - OSPF, EIGRP, RIP.

Question 36. What Is Default Route?

Answer :

A default path specifies a course that the router should take if the vacation spot is unknown. All the lP datagrams with unknown vacation spot deal with are sent to the default direction.

Cisco Nexus switches Interview Questions
Question 37. Define Static Routing?

Answer :

In Static routing routes are manually configured on the router by using a community administrator. 

Static routing has the subsequent Advantages - 

There is no overhead on the router Cpu. 
There is no bandwidth utilization among routers. 
Lt is comfortable because the administrator can pick to allow routing get entry to to certain networks handiest. 
Static routing has the subsequent Disadvantages - 

The administrator should genuinely apprehend the internetwork and the way each router is connected which will configure routes correctly. 
Lt is not possible in big networks due to the fact maintaining it is a complete-time job. 
Question 38. What Is The Command To Backup Ios To Tftp Server?

Answer :

#copyflashtftp

 

Question 39. What Is The Command To Copy Running-config To Startup Config?

Answer :

# copy going for walks-config startup-config

Question 40. What Is The Command To Display The Current Running Configuration?

Answer :

# show going for walks-config 

Router Interview Questions
Question 41. What Is The Command To Reboot A Router?

Answer :

# reload 

Question 42. What Is The Command To Enter Global Configuration Mode From Privilege Mode?

Answer :

# configure terminal 

Multiprotocol Label Switching (MPLS) Interview Questions
Question forty three. What Is The Command To Enter Privilege Mode From User Mode?

Answer :

> allow 

Question 44. What Are The Different Modes In Router?

Answer :

User Mode> 
Privilege Mode # 
Global Configuration Mode #(Config) 
Each Mode has get right of entry to to exclusive set of lOS instructions. 

Question 45. What Is Rom Monitor?

Answer :

If the Bootstrap application isn't always able to discover a legitimate lOS photograph, it'll act as ROM Monitor. 

ROM Monitor is capable of appearing sure configuration mission inclusive of:

Recovering a lost password 
Changing the configuration sign up price and so on. 
Downloading iOS photo the usage of TFTP
Question 46. What Are The Possible Locations Of Los Image?

Answer :

FLASH and TFTP Server. 

Question forty seven. What Are The Different Types Of Memory In Router?

Answer :

RAM: Running configuration document: running-config is stored in RAM 
NVRAM: Start up Configuration record: startup-config is stored in NVRAM 
Flash Memory: lOS is stored in Flash Memory 
ROM: Instructions for POST, Bootstrap program, Mini-lOS is saved in ROM 
Question forty eight. What Is A Router?

Answer :

A Router is a networking device that plays routing that is it routes packets among gadgets which are on exceptional networks. 

Router is a Layer 3 device.