Self Test

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The following questions will help you measure your understanding of the material presented in this chapter. Read all the choices carefully, as there may be more than one correct answer. Choose all correct answers for each question. Don't focus exclusively on these questions. There are no longer any multiple choice questions on the Red Hat exams. These questions test your understanding of the chapter. Getting results, not memorizing trivia, is what counts on the Red Hat exams.

DNS/BIND

1.	Which of the following commands check the setup of the database on your DNS server? dnscheck BIND dig resolve
2.	You have added the addresses for several new servers into your primary DNS server. The zone files are formatted properly, and you've restarted the daemon called named. You advertise the new servers, and your help desk immediately starts getting calls that no one outside your domain can see the new servers. What is the most likely cause? Your servers are not connected to the network. The serial number was not incremented in the zone file. Someone has changed the zone files without your knowledge. The users at the other end are having ISP problems.
3.	Which is an example of a properly formatted MX record? MX 10.mail.domain.com. MX mail.domain.com. MX 10 mail.domain.com MX 10 mail.domain.com.
4.	Where will you find the database files associated with your DNS server? /etc/named /var/named /etc /var/bind

Answers

1.	þ C. dig checks the configuration of the DNS server against the resolv.conf file. ý A, B, and D are incorrect. Neither dsncheck nor resolve are valid commands. BIND refers to the Berkeley Internet Name Domain, the basis for the DNS software.
2.	þ B. Make absolutely sure that the serial number at the top of the zone file is changed each time you revise a zone file. Otherwise, other DNS servers won't know that anything has changed in your domain, and won't update their databases. ý A might be correct if something strange happened to your server, but the original server name still works internally, so your service is still connected to the network. C and D are also not likely scenarios, as root access is needed locally to edit the DNS configuration files and your ISP may or may not know the addresses of your server clients.
3.	þ D. Make sure the preference is defined, and the trailing '.' is included at the end of the record. ý A, B, and C are incorrectly formatted.
4.	þ B. By default, the database files associated with a DNS server are stored in the /var/named directory. ý A, C, and D are incorrect. There are no default /etc/named or /var/bind directories, and only the standard DNS configuration files, named.conf and named.custom, are stored in the /etc/directory. While you could reconfigure /etc/named.conf to point to different directories for DNS database files, the default is /var/named.

Network File System (NFS)

5.	In the /etc/exports file, if we want to export the /data directory as read-only to all hosts and grant read and write permission to the host superv in domain.com, what is the proper entry? /data (rw,sync) superv.domain.com(ro,sync) /data (ro,sync) superv.domain.com(rw,sync) /data (ro,async) *.domain.com(rw,async) /data superv.domain.com(rw,async)
6.	When Linux boots, what configuration file does Linux use to see what NFS shares to mount? /etc/exports /etc/nfs.conf /etc/fstab /nfs/conf
7.	Your company has just suffered an external security breach. As a result, the security group in your department has tightened the screws on all the servers, routers, and firewalls. Up until this point, all user data had been mounted over NFS, but now, nothing works. What happened? The crackers erased the data from your NFS shared directories, and they erased the backups as well. The NFS ports are no longer allowed through the necessary firewalls. The two problems are unrelated. Make sure you have the disk space you need on your servers. The filesystem is no longer shared from the server.
8.	You're experiencing problems with NFS clients for various reasons, including frequent downtime on the NFS server and network outages between NFS clients and servers. Which of the following steps can help address this problem? Remove all firewalls on individual computers inside your network. Avoid setting up mission-critical computers as NFS clients. Always make sure the portmap daemon is active before starting NFS. Configure NFS with 'soft' mounts.

Answers

5.	þ B. This answer exports the filesystem as read-only to all users; it then specifies the computer that gets read/write permission. ý A provides read/write to all general hosts and gives the superv.domain.com computer read-only access. C provides read-only to all but allows all computers on the domain.com subnet to have read/write access. D gives read/write access only to the superv.domain.com computer. The sync and async options can both be appropriate under different circumstances.
6.	þ C. /etc/fstab can be configured with all the necessary information for a computer to mount a shared NFS directory. ý A refers to /etc/exports, which lists the exported NFS directories. However, it does not itself mount an NFS directory. B and D are nonexistent files.
7.	ý B. Ports 111, 745, 747, and 2049 must be open through firewalls to allow NFS to function. Since the security problems associated with NFS may have been to blame for the break-in, it is a good idea to restrict its use to isolated or protected subnets. ý While A, C, and D are all possibilities you should check for, the most likely culprit is B.
8.	þ A, B, C, and D are all to some extent correct. Ideally, you should be able to set NFS on computers inside a 'trusted' network, which means that you can remove firewalls on computers inside that network. If you avoid setting up mission-critical computers on NFS, you'll have fewer problems with NFS. The portmap daemon has to be running before NFS can work. To some extent, D is the best answer, because it can help an NFS client cope with downtime on an NFS server. ý None of the answers are incorrect.

DHCP

9. 

You add a new workstation to your dhcpd.conf file. You're in a hurry to finish, so you save and go to lunch. When you return, your phone mail is full of user complaints that they can't access the Internet, but the local network is fine. You surmise that you accidentally changed something in the dhcpd.conf file. What is the most likely cause?

1. A missing routers command.

2. The subnet mask was changed.

3. The IP range was thrown off.

4. The broadcast address was changed.

Answers

9. 

þ A. The lack of a router declaration in /etc/dhcpd.conf would keep your hosts from getting the gateway address, which is required to access the Internet from an internal network.
ý B, C, and D would probably cause a general network outage.

Keeping Servers in Sync

10. 

Which are proper keywords that can be used in an ntp.conf file?

1. server

2. client

3. sibling

4. child

Answers

10. 

þ A is correct. In /etc/ntp.conf, a server is an alternate time server.
ý B, C, and D are incorrect. The client, sibling, and child commands are not relevant in the ntp.conf file.

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