Interview Questions.

Q1. Explain Ping?

If your trouble isn't always apparent from analyzing 'ifconfig -a' and 'netstat -rn', the ping command can be very beneficial in diagnosing it further. Try strolling 'ping -s gadget-with-no-direction'. There are two possibilities. If you get a few sort of 'network unreachable' or 'host unreachable' blunders, this commonly way that there's no course on your device to the gadget you are trying to ping. You will probable need to define a static course for that device's network, or probable a default course. Following are a few examples. Under SunOS, you may just get the simple '... Unreachable' mistakes: %%%% ping -s lab-manta PING lab-manta: fifty six information bytes sendto: Network is unreachable ping: wrote 150.One zero one.89.28 64 chars, ret=-1 At this factor, you must return to looking at your 'netstat -r' table.

Q2. What Is Traceroute?

If you can't remedy your routing issues via searching on the routing tables and interfaces, a useful program for assisting remedy the problem is traceroute. Solaris 2.7 software bundles the famous traceroute application. Unfortunately, this program isn't shipped with SunOS or Solaris previous to 2.7, and as a result isn't supported by using SunService. However, you can effortlessly discover a reproduction at the internet. The ftp website online ftp.Dfn.De consists of traceroute below the /pub/gear directory. If you consult 'archie' or other searching packages, it is possibly that you will be capable of find a extra neighborhood replica. Traceroute works via sending out a fixed of three UDP packets.

These packets are to start with given a Time-To-Live of 1 hop, which is then improved to 2 hops, then to a few, and many others.... Till the packets reach the far off gadget. This has the impact of stepping thru the routers leading toward a vacation spot machine, one by one. However, it additionally reasons you to only see a unidirectional path, from your consumer to the destination machines. It's pretty feasible for routes to be exceptional going from and to a device, and traceroute will now not standardly show this. For example, if packets observed the following route: --> C --> A B

Q3. What Is Ifconfig?

It is always first-rate to begin investigating routing troubles by using making sure that your interfaces are set up efficaciously. By running ifconfig, you can see your contemporary interface setup: # ifconfig -a lo0: flags=849<UP,LOOPBACK,RUNNING,MULTICAST> mtu 8232 inet 127.0.Zero.1 netmask ff000000 le0: flags=863<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST> mtu 1500 inet 150.One zero one.16.28 netmask ffffff00 broadcast 150.101.16.255 ether 8:zero:20:10:78:d When an interface is brought up, it mechanically creates a course.

This course may be to the neighborhood network for multipoint interfaces (ether, FDDI, TR, and many others), or to a host for factor-to-point interfaces (PPP). If your major interface (le0 in the above example) isn't UP and RUNNING, genuinely no routing will be occurring thru it. If the interface is UP, you will additionally need to examine the inet and netmask entries of your major interface, and make sure they're set efficiently. If the inet is set wrong, take a look at your /and so forth/hostname.Interfacename file (ie, hostname.Le0) and your /etc/hosts document. If the netmask is about wrong, test your /and so on/netmasks report

Q4. How Does /ip Route Check-gateway Work?

Check-gateway sends pings every 10 seconds. If two successive pings fail, the gateway is taken into consideration useless.

Q5. What Is Administrative Distance (advert)?

Administrative Distance is the trustworthiness of a routing protocol. Routers use AD value to pick out the high-quality path when there are  or extra extraordinary routes to the identical destination learned thru  distinctive routing protocols.

Q6. What Is Distance-vector Routing Protocol?

Distance vector routing protocols use the space or hops as metric to discover paths to destinations. 

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

Q7. What Is Ip Addresses, Netmasks And Subnets?

All IP ADDRESSES are divided into two portions: the NETWORK ADDRESS, and the HOST ADDRESS. The community portion of the IP cope with defines the extent at which routing is achieved because of this all machines with the same community address are on the identical network. For instance, if we had the IP cope with a.B.C.D, we would analyze that the community portion of that cope with turned into a.B, and the host part of that cope with became c.D. In that case, all machines with the IP deal with a.B.*.* would be at the equal network. We would typically see a route to the community a.B.0.@By default, Internet IP addresses are divided into three Classes. Each of those ranges has a distinctive portion of the IP cope 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

Q8. What Are The Range Of Ad Values?

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

Routing Protocol Administrative Distance Value 

Directly Connected 0 

Static direction 1 

EIGRP ninety 

OSPF 110 

RIP one hundred twenty 

Q9. What Is Netstat?

You can examine your modern-day routing tables by way of going for walks the command netstat, as follows: %%%% netstat -rn

Q10. What Is A Dynamic Routing?

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

Q11. What Is Default Route?

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 cope with are despatched to the default route.

Q12. What Is The Command To Backup Ios To Tftp Server?

#copyflashtftp

 

Q13. What Is Cdp?

Cisco Discovery Protocol is a CISCO proprietary protocol to assist administrators in gathering statistics about both regionally connected and far flung devices. 

Q14. What Is A Routed Protocol?

A Routed Protocol carries facts from one network to any other network. Routed Protocol contains user visitors 

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

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

Q15. Define Static Routing?

In Static routing routes are manually configured at the router through a network administrator. 

Static routing has the following Advantages - 

There is no overhead on the router Cpu. 

There is not any bandwidth usage between routers. 

Lt is relaxed as the administrator can choose to permit routing get entry to to positive networks handiest. 

Static routing has the following Disadvantages - 

The administrator need to certainly apprehend the internetwork and the way every router is attached so that it will configure routes efficaciously. 

Lt isn't always feasible in huge networks because maintaining it's miles a full-time task. 

Q16. How To Set A Netmask Under Sunos?

In order to consist of a permanent netmask in your SunOS device, you must make an entry in the /etc/netmasks report, inside the following layout: network-deal with-with out-zeroes netmask For example: %%%% cat /etc/netmasks 150.A hundred and one 255.255.255.0 The above would subnet the class B network, one hundred fifty.101.Zero.0, into 254 subnets, from a hundred and fifty.One hundred and one.1.Zero to one hundred fifty.A hundred and one.254.@It is important to notice that the entry in the left hand column need to be the authentic base community number (ie # for a Class A, #.# for a Class B and #.#.# for a Class C), not the subnet.

Q17. What Is Cost?

Cost is the inverse percentage of bandwidth of the links. 

Q18. How To Set A Defaultrouter?

If you need to define a default router, so you can send all of your non-local packets through one popular device, absolutely create the report /etc/defaultrouter. It need to have as its sole contents, the hostname or ipnumber of your router: %%%% cat /and so forth/defaultrouter router-1 or: 150.A hundred and one.Sixteen.1 Note that any machine listed as a defaultrouter _must_ be on the same subnet as your gadget and the name listed in /and so on/hosts. On Solaris 2.4, and later, you can in reality list multiple routers in the /and many others/defaultrouter file, one default router per line: %%%% cat /and many others/defaultrouter router-1 router-2 router-three You additionally want to make certain that every name which appears in /and many others/defaultrouter has an access to your /etc/hosts file:

%%%% cat /and so forth/hosts ... One hundred fifty.One zero one.Sixteen.1 router-1 150.One hundred and one.16.2 router-2 one hundred fifty.One zero one.Sixteen.3 router-three After you have got created /and so on/defaultrouter, and made sure that any names listed in that document are also indexed in /and many others/hosts, you could reboot your gadget. When it comes again up, it will routinely be routing via the defaultrouter which you have described. If you have got a easy network, or in case you are simply seeking to get routing to paintings after your Sun gadget is first set up, you probable need to installation a defaultrouter, as is defined right here. Some similarly advice on what kind of routing to apply. How does a couple of default routes work?

Q19. How To Use In.Routed?

On a SunOS system, in.Routed will mechanically be began if there is no /and so forth/defaultrouter document and in.Rdisc didn't discover any Router Discovery compliant routers at the neighborhood community. In.Routed will routinely start on routers if there is no /and many others/defaultrouter file, despite the fact that in.Rdisc is jogging. In.Routed helps RIPv1 simplest.

You have to no longer need to do anything, aside from possibly deleting an /and so forth/defaultrouter record, so that you can get in.Routed to run. You can pressure in.Routed to convey up widespread community routes through placing entries for them into the record /etc/gateways. The general layout for that report is: internet gateway metric passive or: internet gateway metric energetic faraway-community-ip, gateway-ip and hop-count.

Q20. What Is Link-country Routing Protocol?

Each router strolling a link country routing protocol originates information about the router, its immediately related hyperlinks, and the kingdom of those hyperlinks. This records is sent to all the routers inside the network as multicast messages. 

Link-country routing constantly try to keep complete networks topology through updating itself incrementally handiest while community topology modifications. Example:- Open Shortest Path First (OSPF) 

Q21. What Is Hop Count?

Hop rely is the wide variety of routers from the supply thru which records ought to bypass to attain the vacation spot community.

Q22. What Is Rom Monitor?

If the Bootstrap software is not capable of discover a valid lOS image, it's going to act as ROM Monitor. 

ROM Monitor is capable of appearing sure configuration mission together with:

Recovering a lost password 

Changing the configuration sign in price and so forth. 

Downloading iOS photo using TFTP

Q23. How To Force A Machine To Be A Router?

If your gadget has as a minimum  interfaces in addition to lo0, or in case your device has as a minimum one point-to-factor interface, it will routinely be set up as a router. Solaris 2.X: The IP layer will normally act as a router (forwarding datagrams that aren't addressed to it, amongst different things) whilst the system has two or extra interfaces which are up. This conduct can be overridden through the use of ndd(1M) to set the /dev/ip variable, ip_forwarding. The value 0 manner do no longer forward; the fee 1 way ahead.

Q24. What Is The Command To Enter Global Configuration Mode From Privilege Mode?

# configure terminal 

Q25. What Is A Router?

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

Router is a Layer three device. 

Q26. What Are The Possible Locations Of Los Image?

FLASH and TFTP Server. 

Q27. How To Filter Out The Default Route From Outgoing Bgp Advertisements?

Assuming you have got a static default course this is redistributed because redistribute-static parameter is ready to yes, do the subsequent: 

/routing clear out upload chain=myfilter prefix=zero.0.Zero.0/0 action=discard

Then set myfilter as the out-filter out for BGP instance 

/routing bgp instance set default out-filter=myfilter

Q28. What Is The Command To Reboot A Router?

# reload 

Q29. What Is Hybrid Routing Protocol?

A Hybrid Routing protocol takes the blessings of both Distance Vector and Link State Routing protocols. 

It sends traditional Distance Vector updates. 

Lt has Link State characteristics additionally this means that it synchronizes routing tables between acquaintances at 

startup, and then it sends specific updates when community topology changes. 

Example:- Enhanced Interior Gateway Routing Protocol (EIGRP)

Q30. What Is The Command To Display The Current Running Configuration?

# display walking-config 

Q31. What Is The Command To Copy Running-config To Startup Config?

# copy running-config startup-config

Q32. How To Add Static Routes?

At any time, you could upload static routes for your gadget via the course command. The general syntax for including a community route is: direction add net "far flung-network-ip gateway-ip" 'hop-metric-matter' On Solaris 2.6: course add -internet "far flung-community-ip gateway-ip" -netmask route add -host "host-ip neighborhood-intrf-ip" -interface remote-network-ip is the network you are adding a path to, gateway-ip is the ip deal with of the gateway that ends in that far flung-community. Hop-be counted is an integer which identifies the quantity of gateways that you need to undergo to get to the far flung-community.

A community that is at once related on your system would have a hop depend of zero (ie, the one hundred fifty.101.16.Zero net in the example under). A far flung-network that is without delay linked to a gateway-device that is, in flip, at the same network as your system could have a hop matter of 1 (ie, the 150.A hundred and one.17.Zero internet in the instance underneath). Static routes are rarely delivered for remote-networks with a hop matter extra than 1.

Q33. How To Set A Netmask Under Solaris?

In order to encompass a everlasting netmask in your Solaris device, you ought to make an access within the /and so forth/netmasks record, within the following layout: community-cope with netmask For example: %%%% cat /etc/netmasks a hundred and fifty.One zero one.Zero.Zero 255.255.255.0 The above would subnet the class B community, a hundred and fifty.101.Zero.0, into 254 subnets, from 150.101.1.0 to a hundred and fifty.One hundred and one.254.@In 2.Five.1 and below, only one entry for the complete class network is authorized to assist standard subnetting as specified in RFC-950 It is critical to observe that the entry in the left hand column need to be the unique base community number (ie #.Zero.Zero.Zero 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 changed to help VLSM. It is now feasible to mix the RFC-950 and RFC-1519 form of subnet masks within the netmasks file. The community deal with need to be the "SUBNETTED" address NOT the standard network quantity based at the hosts ip address. (see man web page for netmasks) Here are some examples: A host address 192.188.206.65 with a netmask of 255.255.255.224 /etc/netmasks 192.188.206.Sixty four 255.255.255.224 A host deal with 172.31.16.193 with a netmask of 255.255.255.192 /and many others/netmasks 172.31.Sixteen.192 255.255.255.192

Q34. What Is Egp?

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

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

Q35. What Is A Route Metric?

Routing Protocol makes use of Route Metric cost to discover the fine path while there are  or extra distinctive routes to the equal destination. 

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

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

Q36. What Is An Autonomous System?

An Autonomous System (AS) is a set of networks beneath a unmarried administrative control.

Q37. What Is Routing?

The ROUTING TABLE is a desk maintained in the kernel that determines how packets are routed to other systems. A number of packages may additionally add or delete routes from the routing tables, such as course, ifconfig, in.Routed and in.Rdisc. The routing desk includes 3 kinds of routes: HOST ROUTES are checked first and outline a course to simply one host. NETWORK ROUTES are checked 2nd and define a route to all the hosts on one community. DEFAULT ROUTES are used as a catch-all, when no host or network routes are located to a vacation spot. They usually ship to a greater informed routing gadget, which has a better risk of being able to find a host or network direction to the destination.

Q38. What Is The Command To Enter Privilege Mode From User Mode?

> permit 

Q39. What Are The Different Modes In Router?

User Mode> 

Privilege Mode # 

Global Configuration Mode #(Config) 

Each Mode has get entry to to one-of-a-kind set of lOS commands. 

Q40. What Are The Different Types Of Memory In Router?

RAM: Running configuration report: going for walks-config is saved in RAM 

NVRAM: Start up Configuration record: startup-config is stored in NVRAM 

Flash Memory: lOS is saved in Flash Memory 

ROM: Instructions for POST, Bootstrap application, Mini-lOS is stored in ROM 

Q41. How To Force A Sunos Machine Not To Be A Router?

If you do now not want your more than one-interface SunOS machine to course packets, you'll need to rebuild the kernel. In the document /sys/netinet/in_proto.C, alternate the following line: #outline IPFORWARDING 0 to read: #outline IPFORWARDING -1 Afterwards, config the kernel, remake it, after which installation it. It can be useful to word, that on SunOS machines, IPFORWARDING could have three values: -1 Never ahead IP packets zero Don't ahead, but trade IPFORWARDING to 1 if there are  or extra interfaces 1 Always ahead IP packets

Q42. What Is Igp?

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

Q43. What Is Routing Protocol?

Routing Protocols examine the routes and offer the high-quality routes from one network to any other network. 

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

OSPF (Open Shortest Path First). 

Q44. What Is Bandwidth, Delay, Reliability, Load?

Bandwidth - It is the Data capability of a link in Kbps. 

Delay - It is the time takes to reach the vacation spot. 

Reliability - The path with the least amount of errors or downtime. 

Load - It is the amount of usage of a path. 

MTU - Maximum transmission unit (MTU) defines the maximum Layer 3 packet that can be despatched over a medium. 

Q45. How To Use In.Rdisc?

The in.Rdisc daemon is simplest to be had on Solaris system it depends on multicasting, which isn't present on older SunOS machines. If you do no longer have an /etc/defaultrouter record on a Solaris system, any routing host will robotically convey up in.Rdisc at boot time. As long as there is at least one router at the same network which advertises Router Discovery messages, in.Rdisc will continue going for walks. If not anything responds to the preliminary Router Discovery queries, in.Rdisc on a routing host will robotically give up, and the rc files will fall through to in.Routed. Solaris routers will also routinely carry up in.Rdisc at boot time, if there is no /and so on/defaultrouter file.

They will not ever exit, but as an alternative will put it on the market thru Router Discovery messages. If you want in.Rdisc to run, you have to by no means should do anything, other than delete the /and so forth/defaultrouter report, if it exists, and ensure that at the least one Router Discovery compliant router exists at the identical subnet as your device. If you need to disable in.Rdisc, you ought to sincerely rename it: %%%% mv /usr/sbin/in.Rdisc /usr/sbin/rdisc.Shop In trendy, in.Rdisc have to handiest be run on routing hosts if your nearby community is quite complicated.

Q46. What Is Arp?

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 ordinary routing protocols have finished their paintings, ARP springs in to motion. It's what definitely gets packets from one gadget to every other. Usually, you need to now not ought to fear about ARP at all. Except in unique setups, it should work totally transparently.

Q47. How To Force A Solaris Machine Not To Be A Router?

If you do not need your multiple-interface device, walking Solaris 2.Four or lower, to direction packets, you simply need to make a small change to the report /etc/init.D/inetinit. Find the following two strains: numifs=`ifconfig -au grep inet wc -l` numptptifs=`ifconfig -au grep inet egrep -e '-->' wc -l` And right away after them, insert the following: numifs=2 numptptifs=0 After the machine next reboots, it's going to no longer act as a router.

If you're the use of Solaris 2.Five or greater, it is even simpler to make your machine not path packets. Simply create an /and so forth/notrouter report: %% contact /and many others/notrouter Afterwards, reboot the system. It may be beneficial to be aware, that on Solaris machines, ip_forwarding can have three values: zero Never Forward 1 Always Forward 2 Only ahead while two or more interfaces are up The above steps bring about the ndd /dev/ip ip_forwarding variable being modified from "1" to "0", which prevents routing.

Q48. How Routing Starts Up?

Solaris and SunOS each have a particular order which they use to begin up routing: If an /and so on/defaultrouter document exists, best static routing might be used, and a static default direction could be created to the system listed in the defaultrouter report. If there is no /and many others/defaultrouter document, and the machine is a router, both in.Routed and in.Rdisc may be started, and they'll put it on the market routing facts. SunOS machines will simplest begin up in.Routed, as in.Rdisc isn't always to be had below SunOS. If there may be no /and so forth/defaultrouter record, and the machine is a bunch, in.Rdisc is initially started out.

If any machines on the same community put it on the market via Routing Discovery, in.Rdisc may be used because the dynamic routing program if there aren't any machines marketing thru Routing Discovery, in.Rdisc will fast stop. SunOS skips this step. Finally, if there is no /and many others/defaultrouter report, and both the system is walking SunOS, or in.Rdisc has failed, then in.Routed is started out. It will listen for different in.Routed packages marketing thru RIP packets. This is the default way in which most out-of-the-field Suns will operate.