ccna 200-301 rip

ccna 200-301 rip.A good solution is to configure NTPoNTP in the network can make the time of all routers in the network synchronized with the NTP server. A group of NTP clients that get their time and date information from a single source can maintain a consistent time setting. When NTP is implemented in a network, it can be set to synchronize with a private master clock, or it can be set to synchronize with a public NTP server on the Internet.NTP uses UDP, port number 123, as described in RFC 1305.2.3.5.2 NTP ServersWhen determining whether to use private or public clock synchronization, weigh their risks and benefits.If a private master clock is used, it should be synchronized with Coordinated Universal Time (UTC) via satellite or radio. Administrators must ensure that the time source is valid and from a secure site; otherwise, it will pose a security risk. For example, an attacker could launch a DoS attack on the Internet by sending forged NTP data to the network to change the clock of a network device, which could render the digital certificate invalid. An attacker can also disrupt the clock of a network device during an attack, leaving administrators at a loss. For administrators, this makes it difficult to determine the order in which syslog events occur on multiple devices.Getting the clock from the Internet means allowing unsecured packets to pass through the firewall. Many NTP servers on the Internet do not require authentication of the peer, so network administrators must verify the reliability, validity, and security of the clock. Communication between devices running NTP (also called correlation) is usually statically configured. Each device is given the IP address of the NTP master server (master). By exchanging NTP messages between each interconnected pair of devices, time is kept precisely synchronized. In an NTP-configured network, one or more routers are designated as master clock keepers (also called NTP master servers) using the ntpmaster global configuration command. The NTP client either contacts the NTP master server or listens for messages from the NTP master server to synchronize the clock. To contact the NTP master server, use the ntpserver ntp-server-address command.In a LAN environment, NTP can be configured to use IP broadcast messages instead of the ntpbroadcastclient interface configuration command. Since each device can be configured to send and receive broadcast messages, this alternative reduces the complexity of configuration. The accuracy of time synchronization is also reduced because the flow of information is unidirectional.2.3.5.3 NTP AuthenticationThe time held by the device is critical, so the security features of NTP should be used to avoid accidental or human error in setting the time. There are two available security mechanisms.ACL-based restrictions; Cryptographic authentication mechanisms provided by NTPv3 or later. NTPV3 or later supports cryptographic authentication mechanisms between NTP peers. In addition to specifying which network devices are allowed to synchronize with other network