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As a senior network administrator, you receive complaints from server team that yesterday there were multiple short network cuts that impacted some very sensitive applications running in the data center. You investigate and find out that one of the level 1 network engineers performed some network changes. What went wrong?

This article discusses the solutions for quiz 15. Yes, I know, I know... it's about RIP ! But you need to be ready for anything when facing the challenges of a CCIE exam. Read along to review some things about auto-summarization (which is "on" by default).

This article is a continuation of previous post about RIP Auto-Summarization and it's impact on discontiguous networks in Cisco networks, but this time from Juniper's perspective. Using the default auto-summary on Cisco devices can lead to routing loops in case of discontiguous networks, as shown in quiz 15.

Your company uses multi-vendor routing platforms (Cisco and Juniper) and has multiple sites connected via MPLS from a service provider. Each remote site has a GRE tunnel with the Headquarter (HQ) and a BGP session over this tunnel. After some security change in the network, sites that are Juniper-based behave differently than the Cisco-based ones, creating outage for the customer. What's wrong?

This article discusses the solutions for quiz 14 and it describes some scenarios to help understand why redistributing iBGP into IGP (OSPF in this case) is dangerous.

Your company decided to replace the existing Cisco devices with Juniper. The network team does that and configures the new Junipers as similar possible to the old Ciscos. But something does not work as intended. What is it ?

This is the solution for quiz-13 that covers Frame Relay, a topic that is very hard to find it implemented in today's networks but often seen during certification exams, as it still part of the curriculum for some of them. This is about differences between static and dynamic frame relay mappings.

Company ABC is in process of configuring BGP Confederations between its sites. During a small transition period, there will be no BGP between R3 and R2, but instead only static routing. Have a look at the quiz and try answering the question !

Your network is up and running without any complaints for few months. All good, until one single link creates problems in the entire network, although it was supposed to be redundant. What's wrong ?

Here I come with the solution for quiz-12, that I consider to be one of the most difficult quizes published on this blog, until now. Forwarding Address (FA) is not quite a common nor easy to understand topic. Read to find out more.

Your network follows a standard 3 tier hierarchical design (Core, Distribution, Access) and has two WAN circuits with eBGP sessions with the ISPs. You want to push the default route down to the Distribution routers, but something goes wrong. Where is the mistake?

This post represents the solution and explanation for quiz-11. A very important topic when configuring Network Address Translation (NAT) is the order of operation. Who is performed first: NAT or Routing ?

You have recently joined a new company that still uses Frame Relay. For monitoring purposes, you implement a script that pings all interfaces of a router, but you notice that some of them are not ping-able. Why ?

This post represents the solution and explanation for quiz-10. It describes the functionality of the Down Bit in preventing routing loops in your network.