Sunday, 24 June 2018

What is EIGRP (Enhanced Interior Gateway Routing Protocol).


EIGRP stands for Enhanced Interior Gateway Routing Protocol. It advanced distance-vector routing protocol and also called Hybrid protocol. It uses DUAL (Diffusing Update Algorithm) for determine best the path in network. EIGRP designed by the CISCO and only runs on CISCO routers and some CISCO switches. In 2013 EIGRP convert in open standard protocol and in 2016 EIGRP defined in RFC 7868.

EIGRP is a dynamic protocol because it automatically shares route information. In same autonomous system by using EIGRP a router share own routes to others routers and every router manage a routing table. When routing table changes then EIGRP only sends only changeable updates. 

EIGRP reduce the router workload. Each router sends hello packets for know own neighbors if any router don't send hello then it’s inactive. EIGRP uses for multicast address and protocol number 88.

EIGRP Features:-

EIGRP has many useful features that make it especially useful in large area network and complex network.

EIGRP supports VLSM and CIDR. CIDR stands for Classless Inter-Domain Routing and VLSM stands for Variable Length Subnet Mask.

EIGRP supports load balancing and uses different authentication password at different times. It's uses MD 5 and simple text authentication.

EIGRP Communication via Reliable Transport Protocol (RTP) and it not do broadcast.

EIGRP don’t sends entire routing table. It sends only changes if route changed. The default AD (Administrative Distance) value is 90.

By default EIGRP allows 100 hop counts but we can change and set hop counts 1 to 255. EIGRP maximum allows 255 hop counts.

Monday, 18 June 2018

What is OSPF (Open Shortest Path First).


OSPF stands for Open Shortest Path First. It’s an Interior Gateway Protocol (IGP) for the internet and used for exchange the routing information between autonomous systems. Open Shortest Path First is a link state protocol, in link state protocol the routers exchange topology information with their nearest neighbours.

OSPF designed by the Internet Engineering Task Force (IETF). OSPF firstly introduced in 1989 and defined in RFC 1131 and it’s also known as OSPF version 1. The OSPF version 2 published in 1998 for IPv4 and defined in RFC 2328. In 2008 OSPF version 3 published for IPv6 and defined in RFC 5340.

OSPF mainly used in large enterprise networks and its supports classless inter domain routing (CIDR). It uses Dijkstra’s algorithm and this Dijkstra’s also known as Shortest Path First (SPF) algorithm. Because it link state routing protocol, it’s based on link state algorithm which developed by the ARPHANET in 1980. OSPF was developed to calculate the shortest path in network.

OSPF Features:-

The OSPF hello timer is 10 seconds and hold down timer is 40 seconds. If the any doesn’t reply within 40 seconds then OSPF remove it from own neighbour table.

The biggest advantage of OSPF, it allows unlimited hop counts. Whereas RIP allows only 15 hop counts and the EIGRP allows 255 hop counts.

The OSPF metric is Cost and the Administrative Distance (AD) is 110. Whereas the RIP Administrative distance is 120 and the EIGRP Administrative distance is 90. So the EIGRP is better than OSPF and RIP.

The OSPF supports authentication and its multicast address is All updates are sends through multicast address.

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Saturday, 9 June 2018

What is RIP and version of RIP.


RIP stands for Routing Information Protocol. It’s a distance vector protocol. This protocol based on the Bellman-Ford algorithm. According to the Bellman-Ford algorithm it computes shortest paths for one network to another network. Routing Information Protocol one of the oldest protocol for defines a way of routers. By IETF (Internet Engineering Task Force) the Routing Information Protocol classified as an Interior Gateway Protocol (IGP).

In every 30 seconds RIP sends the routing table of all active interfaces. By default RIP allows 15 hop count. If a destination is 16, it would be unreachable. RIP easy to configure because it’s doesn’t require any parameters or protocols.  RIP better for small area network because it’s allow maximum 15 hop count. By hop count limitation RIP help to stops routing loops. For controlling routing loop or routing loop solutions RIP uses Split Horizon and Route Poisoning and Hold Down mechanisms. The RIP is not best choice for routing because its scalability and coverage are not better than EIGRP, IS-IS or OSPF.

RIP Versions:-


RIPv1 was written by the Charles Hedrick and published in 1988 and defined in RFC 1058. RIPv1 uses classful routing. In classful routing the routing updates do not carry subnet mask or subnet information. It means all devices that are available in network must be configuring with same subnet mask or same class. RIPv1 not support for router authentication.


RIPv1 came with many shortcomings. For remove RIPv1 shortcomings the RIPv2 launched. RIPv2 developed in 1993 and last standardized in 1998 and defined in RFC 2453. RIPv2 comes with classless routing. In classless routing the routing updates carry subnet mask or subnet information. In RIPv2 the route tags were added, they allow distinction between routes learned from RIP protocol and routes learned from other protocols.

How to configure RIP:-

I am configuring a simple lab with RIPv1, which is easy for beginners to understand. 
I have taken three routers and three computers and set the router name R1, R2 and R3. After that i set up ip address for all router interfaces. Now I configure RIP.

Configure RIP R1 Router:-

R1(config)#router rip
R1(config)#network                                       (After run exit command)
R1# copy run start                  (Run copy run start command for save configuration)

Configure RIP R2 Router:-

R2(config)#router rip
R2(config)#network                           (After run exit command)
R2# copy run start           

Configure RIP R3 Router:-

R3(config)#router rip
R3(config)#network                                       (After run exit command)
R3# copy run start           

Note- After configures all router, run router#show ip route command for see routes.

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Monday, 4 June 2018

What is NFS and version of NFS.


NFS stands for Network File System. NFS is a Distributed File System protocol and originally developed by Sun MicroSystems in 1984. Distributed file system do not share block level address to the same storage but use a network protocol. These are commonly known as network file system. The NFS allowing a client computer to access file over a computer network. Such as local storage is accessed. The NFS builds on the Open Network Computing Remote Procedure Call (ONC RPC) system.

The NFS is an Open Standard who's defined in RFC (Request For Comment) and allowing anyone to implement the protocol.

NFS Versions:-

The Sun MicroSystems use NFS version one for experimental purpose. After this the development team done some changes and they decided to release NFSv2.


Network File System version second published on March 1989 and defined in RFC 1094. The NFSv2 originally operated only UDP (User Datagram Protocol). 

In February 1986 using Eunice, implementation were demonstrated for operating system such as System V release 2, DOS and VAX/VMS. Due to 32bit limitation the NFSv2 only allows to read first 2GB of a file. 


Network File System version third published on June 1995 and defined in RFC 1813. The NFS version third supports 64bit file size and handle files larger than 2GB.


Network File System version fourth published on December 2000 and defined in RFC 3010 and revised in RFC 3050. In April 2003 again revised in RFC 7530.

The NFSv4 determine by Andrew File System (AFS) and Server Message Block (SMB). SMB also known as CIFS. In NFSv4 includes performance improvements, strong security and introduces a Stateful protocol. The NFSv4 became the first version who's developed with the Internet Engineering Task Force (IETF).

  • NFSv4.1 published on January 2010 and defined in RFC 5661.
  • NFSv4.2 published on November 2016 and defined in RFC 7862.

Friday, 18 May 2018

Three-Layer of Hierarchical Model by Cisco

The Cisco designed hierarchical model for network design. Its divides network into three layers. The first layer is Core layer and the second layer is Distribution layer and third layer is Access layer. When we used hierarchical model properly, it’s makes networks predictable. The hierarchical model defines which areas should perform certain functions. When we work with large networks, the large networks extremely complicated with multiple protocols and detailed configuration and diverse technologies.  Hierarchical Model helps us to understand the collection of details in networks.  The Cisco hierarchical model help for network implement and maintain and reliable and cost effective. Each layer is responsible for specific responsibilities. These three layers are logical and not necessarily for physical devices.


Core Layer:-

This layer is the core of the network. The Core layer is responsible for transporting large amount of traffic. It’s also responsible for reliably and quickly. The Core layer is switches traffic as fast as possible. If core is failure every user can be affected because the Core layer manages large volume of traffic, so speed and latency are driving concerns here.

Distribution Layer:-

The Distribution layer also known as Workgroup layer. The Distribution layer is communication point between the core and access layer.
The Distribution layer primary functions are provides routing, filtering and WAN access. This layer decides how packets can access the core, if needed. 

Access Layer:-

The Access layer sometimes knows as the Desktop layer. The Access layer controls user and workgroup access to internetwork resources.

Sunday, 13 May 2018

What is FTP?


FTP stands for File Transfer Protocol. FTP is based on TCP. The FTP was written by Abhay Bhusan and published as RFC 114 on 16 April 1971. Its network protocol and used for files transfer between client and server on computer network. File transfer protocol built on client server model architecture for uses separate connection between client and server. FTP user may authenticate with a clear-text sign-in protocol, like as username and password.

FTP encrypts the content and protects the username and passwords for secure transmission, FTP secure with SSL or SSH (Secure File Transfer Protocol). Before Operating System has Graphical User Interface, the client application used FTP server on command-line interface. Many FTP client and automation utilities have been developed for desktop and server and mobile, hardware.

File Transfer Protocol Modes:-

File Transfer protocol works on active and passive mode. Both mode were updated in September 1998 to support IPv6. In both modes the client creates a TCP control connection.

Active Mode:-

In active mode the client established connection with server and FTP server listens on port number 21 (Command Port) and client connect to server on port number 21. Client tells own data port to server and the server send acknowledge to client port for verify the connection.
When the client request some data for server the server send data on particular port. In active mode the data transfer is being actively handled by the server.

Passive Mode:-

When user using firewall and unable to able receive incoming TCP connections, then we can use passive mode. In passive mode the client send a PASV command to server for control the connection. After this the client receives server IP address and server port number. The client uses this IP address and server port number to open data connection.

Thursday, 1 March 2018

What is BGP?


BGP stands for Border Gateway Protocol and it’s a routing protocol. BGP is an exterior gateway protocol that’s designed to exchange routing and reachability information and connects autonomous systems (Autonomous system is a collection of connected Internet Protocols). Currently the internet is working with the help of BGP. BGP mostly used by ISP (Internet service Provider).

BGP not link state protocol and not distance vector protocol, BGP is Path vector routing protocol but sometimes also classed as a distance-vector protocol.

The BGP makes routing decisions based on path and network policies. BGP is also making core routing decisions. BGP has been use on the internet since 1994.

Current version:-

Version 4 is the current version of BGP and this version was published as RFC 4271 in 2006, after progressing through twenty drafts from documents based on RFC 1771 version 4. RFC 4271 corrected errors, clarified ambiguities and updated the specification with common industry practices. The major enhancement was the support for Classless Inter-Domain Routing and use of route aggregation to decrease the size of routing tables.

BGP Uses:-

BGP used for routing in autonomous system. BGP version 4 is standard of internet routing. BGP required of most internet service providers (ISPs) to establish routing between one another. Very large private internet protocol (IP) use BGP internally. It is referred to as interior border gateway protocol, internal BGP, iBGP. In contrast, the internet application of the protocol may be referred to as Exterior Border Gateway Protocol, External BGP and eBGP.

BGP neighbours, called peers. Peers are established by manual configuration between routers to create TCP session on Port 179. BGP sends 19 bytes every minute for maintain the connection. When BGP runs between two peers in same autonomous system, it is called Internal BGP (IBGP). When BGP runs between different autonomous systems, it is called external BGP (eBGP).

Monday, 5 February 2018

Check Out the 3 Reasons You Should Go For CISSP Certification

Before going for CISSP certification, let’s explore the reasons you should go for this certification and the impact this certification would have on your career.
What Is CISSP?
CISSP stands for Certified Information Systems
Security Professional
. The credential is administered by ISC2. This certification is an advanced-level credential ideal for the IT security professionals with a minimum of four years of professional experience in the field of information security. The certification focuses on Access Control, Telecommunications and Network Security, Information Security Governance and Risk Management, Software Development Security, Cryptography, and many more.

The Reasons For The CISSP Certification:-

1. Immense Popularity:-
The CISSP credential is an admired certification for most professionals and is highly respected by a majority of large, global companies like Google, P&G, IBM, and many more. The CISSP certification demonstrates an individual’s working knowledge of information security and commitment to their profession. In 2017, there are 111,000 certified professionals worldwide, and two-thirds of them are from the USA.

 2. Career Prospects And Salaries:-

CISSP certification offers many career prospects and a high salary for the certified professionals. The average salary for the CISSP certified professionals is USD 121,729. The average salary for the CISSP certified professionals is as follows:
·         Security Engineer: USD 131,020
·         Security Architect, IT: USD 153,811
·         Information Security Officer: USD 140,874
·         Information Security Analyst: USD 116,694
·         Information Security Manager: USD 139,677

 3. Catapult your career:-

Information security is a critical aspect of any organization and with a CISSP credential, you may find their job evolving into something even bigger. Here are some threats that a CISSP certified professional combats:
·         Phishing Attacks: A fake web page is created mimicking real page to gather sensitive user information.
·         Close-in Attacks: Stealing data in close physical adjacency.
·         Exploit Attacks: Zero-day attack existing vulnerability in code exploited.
Check out the CISSP certification courses offered by uCertify. The courses fulfill all the three reasons and provide the complete coverage of exam objectives. So, get yourself enrolled in the courses for passing the certification exam in your attempt.
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Saturday, 20 January 2018

Layer 3 Switch

Layer 3 switch:-

Layer 3 switch also known as multilayer switches and it works on Network Layer in OSIModel. These switches act as a router because it has making routing decision. Layer 3 switch require advanced technology and they are expensive. 
Layer 3 switches use in large LAN networks. 

These switches totally based on IP address and stored in the header of IP datagram. Routers use microprocessors to make forwarding decision in software but switch performs only hardware-based packet switching.

How to Layer 3 Switches Works:-

Layer 3 switch works like a layer 2 switch. Layer 2 switch works on Data Link Layer and it uses MAC address for sending data but layer 3 switch works on Network Layer and it uses IP address for sending data. 

Layer 3 switches maintain a IP table. When IP address not match in IP table they broadcast a message in the network and update the table.

Advantages of layer 3 Switches:-

  •  Layer 3 Switches act as a router because it has IP routing table.
  • Layer 3 switches have fast hardware-based packet forwarding.
  • It’s gives high-performance packet switching and high-speed scalability.
  • Layer 3 switches Uses low latency and lower per-port cost and manage flow accounting and gives quality of service.

      Disadvantages of layer 3 Switches:-

  • Layer 3 switches are more expensive than traditional switches.
  • Configuring and VLANs also require additional effort.
  • Layer 3 switch no use for home network or small network.

Wednesday, 10 January 2018

What is ARP and how ARP works?


ARP stands for Address Resolution Protocol. ARP is a request-response protocol and its messages are encapsulated by a link layer protocol. ARP is a communication protocol and it’s used for mapping IP address (Internet Protocol) to a physical address (The Physical address also known as MAC address, MAC stands for Media Access Control and it is a 48 bit address). ARP was defined in 1982 by RFC 826 and it’s an internet standard STD 37. In IPv6 networks, the ARP functionality provide by NDP (Neighbour Discovery Protocol).

ARP using a table for maintains IP address and MAC address, it’s called the ARP cache. ARP has implemented with many combination of network and data link layer technologies, such as IPv4, PUP (PARC Universal Packet) using IEEE 802 standards, Chaosnet, DECnet and Xerox, FDDI, X.25, Frame relay and ATM (Asynchronous Transfer Mode).

How ARP works:-

When we send a packet from one computer to another computer, the packet arrives at a gateway. The gateway asks the ARP to find MAC address that matches with IP address

The ARP checks MAC address in ARP Cache. If the address finds, the packet converted in the right packet length and format and sent to the destination. If address is not founds with IP address, the ARP broadcasts a request packet in the network, if any computer knows it's my IP address, then computer send an acknowledgment to ARP. ARP updates the ARP cache for future reference and then packet send to the destination.

Types of ARP:-

          1.   ARP

          2.   RARP

          3.   IARP

          4.   Proxy-ARP

          5.   Gratuitous ARP

Saturday, 6 January 2018

What is NTP and why correct time is important in network.


NTP stands for Network Time Protocol. Network time synchronization technology was first used in 1979. NTP was designed by David L Mills in University of Delaware. NTP used for clock synchronization between computer systems or data network. NTP server that’s connects through the internet to an atomic clock. This time can then be synchronized through the network to keep all routers, switches, servers etc. receiving the same time information. NTP is one of the oldest protocols that are used in current. NTP uses UDP (User Datagram Protocol) protocol. NTP works on port number 123.

NTP synchronize all participating computer within few milliseconds of UTC (Universal Time Coordinated). UTC is a coordinated time scale and maintained by the Bureau International de Poids at Mesures (BIPM). It is also known as “Z Time” or “Zulu Time”. NTP uses the intersection algorithm, a modified version of Marzullo’s algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time over the public network. 

How NTP works:-

The NTP client send request to NTP server for asks the right time. The server checks the client wrong time and send acknowledgements with the right time. Then client open this acknowledgement and set automatically set the time.

Why correct network time is important in network:-

By correct time, tracking of events are allows on the network in correct order.

Clock synchronization is critical for the correct interpretation of events within the syslog data.

Clock synchronization is critical for digital certificates.

Wednesday, 3 January 2018

What is IP address and classes of IP address?

IP (Internet Protocol):-

IP stands for Internet Protocol. An IP address is a software address and it’s not hardware address. The IP address use for finding hosts on a network. By IP address, devices communicate with other devices on network. 

An IP address serves two principal functions, host or network interface and identification and location addressing. IP address is managed by the IANA (Internet Assigned Number Authority). Each ISP assign an IP address to each device connected to its network.

IP Versions:-

IPv4 (internet Protocol version 4):-

The internet protocol version 4 is used in 1983. Internet protocol 4 is a 32 bits address and it’s provides 4294967296 network addresses. IPv4 reserves some IP addresses for special purpose such as multicast addresses and private networks. 

IPv4 addresses are usually represented in dot-decimal notation, it’s consisting of four decimal number, each ranging from 0 to 255 and separated by dots (such as IPv4 each part represents a group of 8 bits of the address. We can call octets.

IPv6 (Internet Protocol version 6):-

Internet protocol version 6 is a 128 bits address and it’s separated by colon (such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334). An IPv6 address represents as eight groups of four hexadecimal digits, each group representing 16 bits.

IP version classes:-

Internet protocol has five classes:-

Class A:-

Class A addresses are assigned to network with a very large number of hosts. The high order bit in a class A address is always set to Zero and the next seven bits complete the network ID. The remaining 24 bits represent the host ID. 

The class A address range between to Class A supports 16 million hosts on each network. It’s subnet mask is

Class B:-

Class B addresses are assigned to medium size to large size networks. The two high order bits in a class B address are always set to binary 1 0. The next 14 complete the network ID. The remaining 16 bits represent the host ID. 

The class B address range between to Class B supports 65000 hosts on each 16000 of networks. It’s subnet mask is

Class C:-

Class C addresses are used for small networks. The three high order bits in a class C address are always set to binary 1 1 0. The next 21 bits complete the network ID. The remaining 8 bits represent the host ID.

The class C address range between to Class C supports 254 hosts on each of 2 million network. It’s subnet mask is

Class D:-

The class D address range between to This class is reserved for multicasting.

Class E:-

The class E address range between to This class reserved for future use or research and development purposes.


1. is loopback address.
2. addresses used to communicate with the current network.
3. ss link-local addresses (APIPA)
4. /8 represent class A subnet mask (
5. /16 represent class B subnet mask (
6. /24 represent class C subnet mask (