Cisco 350-401 How to deal with various network interview questions?

The interview asked "the server is not responding" when the client accesses the server, how to troubleshoot the problem. How should such questions be answered?



Whether interviewing programmers or network engineers, this interview question is universal, there is no standard answer, the only difference is the depth and breadth of the answer.

Junior engineer
As an entry-level engineer, you should ping the domain name of this website. If you can ping, the domain name resolution is successful and the network connectivity to the server is good.

If there is no ping, what is the IP to check the domain name resolution? If the domain name resolution does not work, ping the name server. If the ping fails, you need to ping your own gateway.

The gateway cannot be pinged, and you need to ping your own IP. If Ping 127.0.0.1 fails to connect, the TCP / IP protocol stack is faulty, or the local firewall is not working properly.
If Ping can ping itself, but cannot ping the gateway, then the gateway may be down, or the network cable may be loose, or the gateway may be filtering out your blacklist.
This toss, 80% probability can locate what the problem is.

mid-level engineer
If you cannot locate the problem in the above troubleshooting, you already know how to use packet capture software to troubleshoot, but also learn how to configure filters to filter out the traffic of interest.

See if the three-way handshake can be successfully established, and whether the fields in the TCP Option, especially the size of the MSS, cause a communication failure due to the MSS being too large. Try to modify the MSS as small as 1380 or less to see the effect. If it can be repaired, it is caused by MSS.
If there are only outgoing packets and no returned packets, it means that the packets sent may be filtered by the firewall, or the returned packets may be filtered. Where exactly is filtered out, you can use the IP of the traceroute server to locate it.

Of course, it is also possible that the local IP is blackened by the server. This situation also exists. The server uses an intelligent algorithm to detect that the local IP has attempted to maliciously attack the server, so it is blackened.

Senior engineer
What I want is asymmetric routing, stateful firewall, and the firewall states are not synchronized.
Still wondering whether the IP obtained by DNS domain name resolution is the IP of the real server or is it polluted? Will try to use the scientific method of Internet access, use an international name server to resolve, and try to connect to the server. If the scientific Internet can be connected, then it can be concluded that the domain name resolution may be polluted, or the server may be hacked by a large firewall.

Is there no intersection between the client's TLS version and the server's version?
There are still many possibilities, so I won't list them one by one. The above corresponds to the skills list of three levels of engineers. You can compare and see what knowledge level you are in.

The above is the news sharing from the PASSHOT. I hope it can be inspired you. If you think today' s content is not too bad, you are welcome to share it with other friends. There are more latest Linux dumps, CCNA 200-301 dumps and CCNP Written dumps waiting for you.

Comments

Post a Comment

Popular posts from this blog

How to choose Cisco dumps?

Image
In this era of lack of trust between people, if you want to buy one thing, in addition to buying on a platform such as a regular platform, such as Amazon. Do you still believe in other self-built platforms? I believe many people have the experience of being cheated. lowest The means of defrauding money is: Your good friend comes to borrow money from you, and you have a relationship card with you so that you can lend him money. At this time, according to the normal person’s thinking, this friend has known me for many years that he might not take the money away. Note that it is often the same idea that gives others the opportunity to owe money. If the amount borrowed is not high, then it is okay. Once the amount you borrowed is too large, you should be careful and your money may not be returned! Back to the topic, in this era of lack of trust, how to choose the Cisco dumps have become an important topic. First, when you buy it depends on whether the website's URL link is https
Read more

What is proxy communication?

Image
Is it correct to understand the working level of forward proxy reverse proxy transparent proxy? Forward proxy and reverse proxy (application load balancing, some NG reverse proxy) can be understood as a man-in-the-middle mode. At the same time, both ends establish a TCP connection, and then the man-in-the-middle performs TCP connection between the two ends. Can a transparent proxy be understood as a simple and crude "hijacking" of a passing data packet, without splitting the complete TCP connection into two independent segments. So, in this sense, this kind of transparent proxy is similar to the working hierarchy of NAT devices? Preface I once saw a person write tens of thousands of words to answer a question, and read it after three days. Shocked, what is all this for? These words can produce a book, and it is also a reward for your hard work. However, I think the man has always been happy, but there is no doubt that his reputation (Reputation) is in full swin
Read more

What are CCNP Data Center jobs in Dubai?

Image
  What are CCNP Data Center jobs in Dubai? Over the last few years, Cisco accreditations have gotten popular astonishingly. Undoubtedly, Cisco certifications would be deemed the outright most necessary certificates in the field of computer system networking. About Cisco certifications, there would be an extensive range of choices. To help your career and assist you in opening brand-new doors in your career, you need the ideal accreditations. Cisco introduced its primary certification program in 1998. The essential idea behind the accreditations was to supplement the CCIE or Cisco Certified Internetwork Expert program. Cisco would have extended its qualifications and supplies lots of certifications for experts of all experience levels from that point forward. CCNP Overview: CCNP or Cisco Certified Network Professional is considered the certification available for IT specialists with one year of expert experience in computer system networking. A diploma or equivalent in a significant fie
Read more