DNS and DHCP

DNS and DHCP

DNS is an acronym for Domain Name System which is a way for a computer to convert names to IP addresses. Domain Name System uses port 53 and is a protocol that uses both TCP and UDP. Dynamic Host Configuration Protocol or DHCP is used to set up pools of addresses to dynamically assign IP addresses to hosts on a network. Unless Static IPs are set by an administrator the network functions better using dynamic addressing.

DHCP can assign IP address, subnet mask and default gateway network configurations and works with an IP Helper address to get to the DHCP server. This allows IT teams to configure things like VLANs and allow for an IP Helper to denote the DHCP server on the switch or router. DNS allows the naming of websites to function instead of using IP addresses to go to websites and is more distributed.

DNS

Using TCP and UDP allows DNS to have a faster by default and more lightweight use using UDP and a more secure or larger packet use when needed for TCP. DNS allows for the use of Top-Level Domains, also known as TLDs, that are like the .com or .net domains. Domain Name System uses caches with root servers that are the TLD servers and act essentially as a decentralized name lookup service.

DHCP

DHCP uses UDP ports 67 and 68 using port 67 for the DHCP Server and 68 for clients. This allows for faster and connectionless communication over UDP compared to TCP. DHCP uses the Discover, Offer, Request, and Acknowledge process which is referred to as the DORA process.

Dynamic Host Configuration Protocol uses APIPA (Automatic Private IP Addressing) to address clients that for some reason fail to get an IP address. This APIPA address starts with a 169.254.x.x IP address and can be a DHCP server failure or a duplicate IP address.

Knowledge Byte

Performance based questions are often not addressed in textbooks. These gaps are addressed in doing labs and in a work or lab environment that can help with the application of theory. This is something that you should take care of in your studies because you will be asked PBQ questions on some IT certification exams.

Conclusion

DNS and DHCP are often covered in Information Technology certifications and are both essential. DHCP is used mainly in places where larger amounts of computers are in a small business or enterprise environment. Performance-based questions can be easily overcome with labs, practice or on the job training.

There are some things that you can do with DNS and DHCP that will allow you to expand your skill set like learning the difference between an A record AAAA record, MX record, and a CNAME record. For DHCP learning more with the DORA process will be beneficial with tools like Wireshark.