| Passing the Network+ and CCNA exams demands | | | | they're working, your phone starts going off - users |
| that you know quite a few port numbers, but they're | | | | are suddenly unable to send and receive email from |
| important to know when working with real-world | | | | outside the office. The first thing to ask yourself in |
| networks as well. Before we discuss why, here's a | | | | such a situation:"What has changed since what is now |
| partial list of important port numbers to know for these | | | | broken was working?"In this case, a firewall is being |
| certification exams:Ports 20 and 21 are used by File | | | | installed - but do you know why that would stop |
| Transfer Protocol (FTP).Port 22 is used by Secure | | | | email? Do you know that ports 25 (SMTP), 110 (POP3), |
| Shell (SSH).Port 23 is used by Telnet.Port 25 is used | | | | and 143 (IMAP) must remain unblocked by that |
| by Simple Mail Transfer Protocol (SMTP).Port 53 is | | | | firewall? If you do, you already know how to fix the |
| used by DNS.Port 69 is used by Trivial File Transfer | | | | problem.I can tell you from personal experience that |
| Protocol (TFTP).Port 80 is used by HTTP.Port 110 is | | | | the key to becoming a world-class network |
| used by POP3.Port 143 is used by IMAP.Port 443 is | | | | troubleshooter is mastering the basics, and that |
| used by Secure HTTP (HTTPS).When you're faced | | | | includes knowing common port numbers. And if you're |
| with a list such as this, there's a temptation to ask | | | | a great network troubleshooter on top of being |
| yourself something like this: "Besides passing the exam, | | | | CompTIA Network+ and CCNA certified, you're |
| do I really need to know these port numbers?"The | | | | always going to be in demand -- and that's where you |
| answer is yes. We do a lot of troubleshooting in this | | | | want to be!Chris Bryant, CCIE #12933, is the owner of |
| business, and part of becoming an expert | | | | The Bryant Advantage, home of over 100 free |
| troubleshooter is knowing how things work when | | | | certification exam tutorials, including CCNA and CCNP |
| they're working correctly. That way, when things do go | | | | tutorials. CompTIA Network+, Security+, and A+ |
| wrong ,you can take a structured approach to fixing | | | | certification tutorials are available, also!Visit his blog and |
| them.Let's say that you're in the middle of a relaxed | | | | sign up for Certification Central, a daily newsletter |
| day at your network monitoring console. A consulting | | | | packed with CCNA, Network+, Security+, A+, and |
| company is at your site to install a new firewall. While | | | | CCNP certification exam practice questions! |