Saturday, January 19, 2019

NTP and why 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.
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What is Traceroute


Traceroute is a computer network diagnostics tool. It’s used for displaying the route and delays of packets in an IP network. Traceroute is a command-line interface tool and available in many operation system, like Windows, MACOS, Linux, FreeBSD. Traceroute also uses ICMP (Internet Control Message Protocol) message, but unlike ping it identifies every router in a path taken by the packets. Traceroute is useful for troubleshoot network because it can help identify where exactly the problem is. 

Traceroute Works:-

Traceroute sends a series of ICMP (Internet Control Message Protocol) echo request packets to destination. First series of message has a TTL (Time to Live) parameter set to 1, which means that the first router in a path will discard the packet and send an ICMP (Internet Control Message Protocol) Time Exceeded message. TTL (Time to Live) is then increased by one until the destination host is reached and an ICMP (Internet Control Message Protocol) echo reply message is received. Main host can then use received ICMP (Internet Control Message Protocol) message to identify all routers in a path. The TTL (Time to Live) vale also known as hop limit.
The traceroute command on windows is named Tracert. On UNIX like system and IOS traceroute it is invoked using the traceroute command.

Example of use “Tracert command” in windows

In this example you can see that the traceroute command has listed the IP address of the routers in the path.

Traceroute on UNIX like OS:-

Traceroute command on UNIX works slightly different than the Windows version. It uses UDP packets with a large destination port number (33434 to 33534) that is unlikely to be used by any application at the destination host. Like the Windows version of the command, traceroute on UNIX uses TTL (Time to Live) to get the IP addresses of the intermediary routers. When a destination host is reached, it replies with an ICMP (Internet Control Message Protocol) port unreachable message.
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What is Ping


Ping stands for Packet Internet Groper. Ping is perhaps the most commonly used tool to troubleshooting a network. Ping (Packet Internet Groper) is included with most operating systems, like available for UNIX and Unix-like operating systems, DOS, Microsoft Windows, and ReactOS. 

Mike Muuss written ping utility in December 1983 during employment at the Ballistic Research Laboratory, now the US Army Research Laboratory. Ping utility was created as a tool for troubleshooting problems in IP networks. Ping was first included in 4.3BSD. It is invoked using a ping command. Ping command uses ICMP (Internet Control Message Protocol) to reports errors and provides information related to IP packet processing. Ping works by sending an ICMP echo request message to the specified IP address. If the computer with the destination IP address is reachable, it responds with an ICMP echo reply message.

A ping command usually outputs some other information about a network performance, for example a round-trip time, a time to send an ICMP request packet and receive an ICMP reply packet.

In the example we have pinged the IP address By default, ping on Windows sends four ICMP request packets. As you can see from the output above, the host with the IP address of is reachable and has replied with four ICMP reply packets. You can also see that the remote host has replied within 1ms (time<1ms), which indicates that the network is not congested.
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NTP and why is important in network

NTP :- NTP stands for Network Time Protocol. Network time synchronization technology was first used in 1979. NTP was designed by David L ...

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