Are You Smarter Than a CCENT? Transport Layer

May 21, 2017 at 11:43 am

Here is a query from a current project – enjoy!

  1. You are examining a packet capture from your local network. What two determinations can you make from this output? (Choose 2)

100-105a. This is a UDP packet
b. This is a TCP packet
c. The target destination is FTP
d. The target destination is HTTP

Correct Answer: b, d

Explanation: Due to its use of reliable transmissions, Transmission Control Protocol (TCP) uses many fields in its packet structure. These include:

  • source TCP port number
  • destination TCP port number
  • sequence number
  • acknowledgement number
  • TCP data offset
  • reserved data
  • control flags
  • window size
  • TCP checksum
  • urgent pointer
  • TCP optional data

In contrast, the unreliable User Datagram Protocol (UDP) packets feature these simple fields:

  • source port number
  • destination port number
  • length
  • checksum

From the destination TCP port number here of 80, you can determine the intended target service is the Hypertext Transfer Protocol (HTTP). Know the following common ports for this exam:

Port Number TCP or UDP Protocol
20 TCP FTP Data
21 TCP FTP Control
22 TCP SSH
23 TCP Telnet
25 TCP SMTP
53 UDP DNS
67, 68 UDP DHCP
69 UDP TFTP
80 TCP HTTP
110 TCP POP3
161 UDP SNMP
443 TCP SSL/TLS
514 UDP Syslog
520 UDP RIP

ICND1 100-105 NAT Quiz!

February 6, 2017 at 8:42 pm

NAT

Good luck with this quiz based on questions from my ICND1 Exam Cram for 100-105!

CCENT 100-105 Configure, Verify, and Troubleshoot Inside Source NAT

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Network Time Protocol

September 21, 2016 at 10:09 pm

Here is another great additional resource from my ICND1 Exam Cram.

Cisco Certification at InformIT! icon

What is a VLAN?

September 20, 2016 at 10:36 pm

Here is another great additional resource from my upcoming ICND1 Exam Cram!

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Stateless DHCP with IPv6

September 20, 2016 at 9:43 pm

Here is another exciting additional resource from the IPv6 chapter of my upcoming ICND1 Exam Cram text! While these configurations are not required of a CCENT/CCNA candidate, I am sure you will agree it is awesome to see them to help nail the concepts home!

Master Basic Networking Today! icon