--- title: "Meaning & Key Takeaway of: For instance, consider the topology in…" description: "\"“For instance, consider the topology in Figure 33-6, with Router R4 on the right acting as NTP server and the other routers acting as clients. R4 has t..." image: "https://sms4smile.com/quotes/i/b86/wendell-odom-19707_quote_for-instance-consider-the-topology-in-fi_1360427.jpg" --- # For instance, consider the topology in Figure 33-6, with… ![“For instance, consider the topology in Figure 33-6, with Router R4 on the right acting as NTP server and the other routers acting as clients. R4 has three IP addresses that the clients could put in their ntp server address commands. Now consider what happens when one interface on R4 fails, but…” quote by Wendell Odom](https://sms4smile.com/quotes/i/b86/wendell-odom-19707_quote_for-instance-consider-the-topology-in-fi_1360427.jpg) [Download](https://sms4smile.com/quotes/i/b86/wendell-odom-19707_quote_for-instance-consider-the-topology-in-fi_1360427.jpg) [Open image](https://sms4smile.com/quotes/i/b86/wendell-odom-19707_quote_for-instance-consider-the-topology-in-fi_1360427.jpg) > ““For instance, consider the topology in Figure 33-6, with Router R4 on the right acting as NTP server and the other routers acting as clients. R4 has three IP addresses that the clients could put in their ntp server address commands. Now consider what happens when one interface on R4 fails, but only one. No matter which of the three interfaces fails, that IP address on that interface cannot be used to send and receive packets. In that case, for any NTP clients that had referred to that specific IP address There would likely still be a route to reach R4 itself. The NTP client would not be able to send packets to the configured address because that interface is down.”” [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) ## About This Quote This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation. If a router interface fails, its IP becomes unusable, though other routes may still reach the router. **In simple terms:** Interface failure blocks its IP. Key Takeaway Design redundancy and monitor interface health. Themes network reliability failover redundancy Mood analytical practical Type technical instructional When to use this quote - data center operations - remote office connectivity - IoT device management Key Concepts IP addressing routing protocols Questions to Reflect On - How will you detect a failed interface quickly? - What fallback mechanisms can you implement? A Different Perspective Redundancy adds cost and complexity. ★ ★ ★ ★ ★ No ratings yet [Clients Ntp](https://sms4smile.com/quotes/about/clients-ntp-4653778/) [Ntp Client](https://sms4smile.com/quotes/about/ntp-client-4653777/) [Ntp Clients](https://sms4smile.com/quotes/about/ntp-clients-4653775/) [Ntp Server](https://sms4smile.com/quotes/about/ntp-server-439283/) [Router R4](https://sms4smile.com/quotes/about/router-r4-4653776/) ## Related quotes > [“Implementing NTP Clients, Servers, and Client/Server Mode With NTP, servers supply information about the time of day to clients, and clients react by adjusting…](https://sms4smile.com/quotes/wendell-odom/implementing-ntp-clients-servers-and-client-server-mode-with-ntp/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“NTP Using a Loopback Interface for Better Availability An NTP server will accept NTP messages arriving to any of its IPv4 addresses by default.…](https://sms4smile.com/quotes/wendell-odom/ntp-using-a-loopback-interface-for-better-availability-an-ntp-server/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“The configuration in Example 33-8 works, but in many cases, routers might have multiple ntp server commands configured for redundancy. The goal is to…](https://sms4smile.com/quotes/wendell-odom/the-configuration-in-example-33-8-works-but-in-many-cases-routers/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) ## More by Wendell Odom > [“Host B can send ICMP echo reply messages to R1’s 172.16.4.1 IP address (hosts send echo reply messages to the IP address from which…](https://sms4smile.com/quotes/wendell-odom/host-b-can-send-icmp-echo-reply-messages-to-r1-s-172-16-4-1-ip/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“NTP Using a Loopback Interface for Better Availability An NTP server will accept NTP messages arriving to any of its IPv4 addresses by default.…](https://sms4smile.com/quotes/wendell-odom/ntp-using-a-loopback-interface-for-better-availability-an-ntp-server/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Storing Log Messages for Later Review With logging to the console and to terminals, an event happens, IOS sends the messages to the console…](https://sms4smile.com/quotes/wendell-odom/storing-log-messages-for-later-review-with-logging-to-the-console-and/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Sending Messages in Real Time to Current Users Cisco IOS running on a device at least tries to allow current users to see log…](https://sms4smile.com/quotes/wendell-odom/sending-messages-in-real-time-to-current-users-cisco-ios-running-on-a/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“System Message Logging (Syslog) It is amazing just how helpful Cisco devices try to be to their administrators. When major (and even not-so-major) events…](https://sms4smile.com/quotes/wendell-odom/system-message-logging-syslog-it-is-amazing-just-how-helpful-cisco/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“172.16.1.51 and vice versa. You can reasonably assume that the switches learned the MAC addresses of the router and the host, adding those to…](https://sms4smile.com/quotes/wendell-odom/172-16-1-51-and-vice-versa-you-can-reasonably-assume-that-the/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Configuring and Verifying System Logging With the information in Table 33-2, configuring syslog in a Cisco IOS router or switch should be relatively straightforward.…](https://sms4smile.com/quotes/wendell-odom/configuring-and-verifying-system-logging-with-the-information-in/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“sending of log messages to all logged users. However, that default configuration is not enough to allow the user to see the log messages.…](https://sms4smile.com/quotes/wendell-odom/sending-of-log-messages-to-all-logged-users-however-that-default/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“First, note that the example configures the same message level at the console and for terminal monitoring (level 7, or debug), and the same…](https://sms4smile.com/quotes/wendell-odom/first-note-that-the-example-configures-the-same-message-level-at-the/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“First, to understand why the standard and extended ping results have different effects, consider first the standard ping 172.16.1.51 command on R1, as shown…](https://sms4smile.com/quotes/wendell-odom/first-to-understand-why-the-standard-and-extended-ping-results-have/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“root cause of the problem may be happening, further isolating the problem. This section begins with a brief explanation of how ping works. It…](https://sms4smile.com/quotes/wendell-odom/root-cause-of-the-problem-may-be-happening-further-isolating-the/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“If the ping works, it confirms the following, which rules out some potential issues: The host with address 172.16.1.51 replied. The LAN can pass…](https://sms4smile.com/quotes/wendell-odom/if-the-ping-works-it-confirms-the-following-which-rules-out-some/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Log Message Format IOS defines the format of log messages. The message begins with some data fields about the message, followed”](https://sms4smile.com/quotes/wendell-odom/log-message-format-ios-defines-the-format-of-log-messages-the-message/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“First, take a moment to review the output of the first IOS ping command. By default, the Cisco IOS ping command sends five echo…](https://sms4smile.com/quotes/wendell-odom/first-take-a-moment-to-review-the-output-of-the-first-ios-ping/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Ping Command Basics The ping command tests connectivity by sending packets to an IP address, expecting the device at that address to send packets…](https://sms4smile.com/quotes/wendell-odom/ping-command-basics-the-ping-command-tests-connectivity-by-sending/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) [Explore all 32 Wendell Odom quotes ](https://sms4smile.com/quotes/author/wendell-odom/) ## More Ntp Server quotes > [“NTP Using a Loopback Interface for Better Availability An NTP server will accept NTP messages arriving to any of its IPv4 addresses by default.…](https://sms4smile.com/quotes/wendell-odom/ntp-using-a-loopback-interface-for-better-availability-an-ntp-server/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“Implementing NTP Clients, Servers, and Client/Server Mode With NTP, servers supply information about the time of day to clients, and clients react by adjusting…](https://sms4smile.com/quotes/wendell-odom/implementing-ntp-clients-servers-and-client-server-mode-with-ntp/) [Wendell Odom](https://sms4smile.com/quotes/author/wendell-odom/) > [“The configuration in Example 33-8 works, but in many cases, routers might have multiple ntp server commands configured for redundancy. 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