Question

How are users categorized?

In Linux, which user has all the privileges?

Why do we need groups for user management?

What is the command to change the root user’s password on Ubuntu?

What are the three files mentioned in this chapter that contain information about a user’s account and the user’s group?

Explain the meaning of each column in the file/etc/passwd.

Explain the meaning of each column in the file/etc/shadow.

Describe the DHCP assigning process.

What are the benefits of using DHCP?

What are the values of the default lease time and the maximum lease time?

Why do we need the name service?

List at least five category-based top-level domains.

What is the maximum number of layers that can be added to the name hierarchy?

What is a root server?

What is a forward lookup process?

What is a reverse lookup process?

Before forwarding the name resolution request to the root server, what does the operating system need to check first?

What is the DNS zone?

What is an NS DNS record?

What is an SOA DNS record?

Answer 1

1. There are three types of users

a. System user

b. Administrator or Root user

c. Normal user

The difference in these users is based on the Uid. System has 0 Uid, has root has 1 to 499 and Normal users from 500 onwards. Normal user needstobe created with useradd command while first two are already in system.

2. Root has all the prviledges, to keeping in mind its safety, some users are given all priviledges and are known as sudo.

3.In Linux groupsare required to organize users. Groups organize collections of accounts, mainly as a security measure. Control of group membership administered through the group file, which shows a list of groups and also its members. Every user must has a default or primary group. When a user logs in, the group membership is set for their primary group.

4. Sudo passwd root, then create password and confirm it.

5. 3 files: shadow file, passwd, group file

6. file/etc/passwd is a text file, which stores essential information required in login ex- user account info

7. file/etc/shadow, it stores the password for the user account in an encrypted format, it stores secure info related to user account.

8. DHCP assigns through IP address pool. first , it broadcast the packet to the client computer,to find server, then the server recieves the packet, then it requests a unicast package, then it got acknowledged.

9. It is automated, global , centralized and subnet specific.

11. We need DNS to resolve human readable address into machine readable IP address. Since humans can't remember all the ip addresses and machine cant understand web address, we need DNS.

12. .com for commercial

.edu for educational

.gov for government purpose

.net for distributed network

.org for organisations

14. A root server works as a part of the supporting infrastructure of the Internet, and makes Internet use by acting as the backbone of online access. Root servers are an essential part of the (DNS). They publish root zone file contents, those are responsible for DNS functionality, for the Internet.

15. Translating between DNS names and IP address are the process of forward lookup and backward lookup

18. DNS zone is a part of DNS, where administrative properties of DNS are held by single manager. It is organised in a hierarchy layout.