Part Three: HP-UX Network Administration

   

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Chapter 26: Basic Network Concepts

1:	What is a protocol?
A:	A protocol is a set of rules and regulations that govern the communication between two computers.
2:	What is the advantage of a layered network model?
A:	The complex task of network communication can be divided into different stages using a layered model.
3:	What are peer protocols?
A:	Peer protocols are used in network communications between two computers having the same layer number.
4:	What is the function of the network layer?
A:	It is used for network addressing and routing.

Chapter 27: Network Components and Topologies

1:	What is an access method? Explain how CSMA/CD works.
A:	An access method is a procedure of accessing a physical medium and sending data over it. In case of CSMA/CD, a station first checks the network medium for any existing network traffic before sending its own data. If the network medium is free, the station starts sending its data. Otherwise, it waits for a random time and retries the transmission. If two stations check the medium and find it free and start sending data simultaneously , a collision occurs which is detected by both stations. The stations then retry transmission after a random period of time.
2:	What is the difference between a hub and a switch?
A:	A hub is a physical layer device, while a switch also covers the data link layer.
3:	Write one characteristic of each of the following network topologies. bus ring star
A:	A bus is inexpensive and easy to implement. A ring is a bus where two ends are tied together. All hosts are connected to a central place in a star topology.
4:	What is the function of a repeater?
A:	It is used to extend the length of a network segment. It regenerates the electrical signal.

Chapter 28: Introduction to the TCP/IP Protocol

1:	What is the use of a netmask ?
A:	A netmask is used to assign a certain number of bits to the network and host parts of an IP address.
2:	What are the major differences between the TCP and UDP protocols?
A:	TCP is a connection-oriented protocol used for reliable data transfer. UDP is a connection-less protocol and does not guarantee reliable data transfer.
3:	What is the use of sockets?
A:	A socket is a combination of an IP address and port number. It is used to provide a virtual connection point for client and server applications.
4:	Why is ARP necessary for network communication?
A:	ARP maps IP addresses to MAC addresses. Without ARP it is not possible to determine to which machine a particular IP address is assigned.

Chapter 29: Configuring LAN Interface Adapters

1:	List the steps involved to configure a network adapter.
A:	Shutdown the system and install a LAN adapter. Install the software driver for the adapter if it is not already there. Use the lanscan command to verify that the adapter is visible. Either use SAM to assign an IP address to the adapter or use the ifconfig command and manually edit the /etc/rc.config.d/ netconf file. Add a routing entry, if needed. Update /etc/hosts . If you are using SAM, this part will be done by SAM.
2:	What does NamePPA mean?
A:	The PPA is the Physical Point of Attachment, while the name is either lan or snap . The combination of the name and PPA (NamePPA) is used in network administration commands.
3:	Is it always necessary to add a default route? Why or why not?
A:	If you have routing entries for all connected networks, there is no need to have a default route. However if your network is connected to a public network, you should define the default route pointing to the router that connects your network to the public network.
4:	What steps can you take if a network adapter is not visible with the lanscan command?
A:	Verify that the adapter is correctly inserted into the system. Verify that driver for the adapter is built into the kernel. If both of the above conditions are met, verify that the adapter is not bad.
5:	Multiple IP addresses can be assigned to a network interface (True/False).
A:	True

Chapter 30: Configuring and Managing ARPA/Berkeley Services

1:	What are the advantages and disadvantages of activating a service using inetd?
A:	If you activate a service using inetd , the server process is started only when needed. The system resources are not used when a server process is not running. However, this may also slow down the response time.
2:	List four Internet services used on HP-UX.
A:	Remote login Remote file transfer Electronic mail Network time protocol
3:	What rules apply to entries in the /etc/hosts.equiv file?
A:	If a remote host name is listed in the file, users of the remote host are allowed to access the local system if the local user name also matches the remote system user name. If the host name starts with a negative sign, access of all users on that system is denied . If a line contains a " + " symbol, it matches every host.

Chapter 31: Host Name Resolution and Domain Name Server

1:	What are the three most common host name resolution methods ?
A:	NIS DNS Hosts
2:	Give a short description of the three types of domain name servers.
A:	The primary name server is an authority for a domain name. Secondary name servers are used to back up the primary server and for load distribution. Caching servers don't have their own data files and are used for name resolutions on a departmental level.
3:	Why is the db.cache file used?
A:	It contains a list of root name servers.
4:	How are DNS data files updated on the secondary server?
A:	These are automatically updated at regular intervals by the secondary server. These can also be updated manually using the sig_named_restart command.

Chapter 32: Configuring and Managing NIS

1:	What is the function of NIS?
A:	It provides centralized information of network resources.
2:	For what purpose are escape entries used in the /etc/passwd file?
A:	These are used to control access for selected users.
3:	What is the difference between NIS and DNS?
A:	DNS provides only host name resolution, while NIS also provides other services. NIS uses a flat name space, while DNS uses a hierarchical name space. A host may participate in only one NIS domain, while it may be a part of multiple DNS domains. NIS can be used on private networks, while DNS is also used on public networks.

Chapter 33: Configuring and Managing the Network File System

1:	How can you grant mount access to an exported file system to selected clients ?
A:	You can use the /etc/exports file to grant mount access to selected clients.
2:	Which subsystems must be present in the kernel to use NFS?
A:	The networking and NFS subsystems must be present.
3:	Why is it necessary to synchronize time on all NFS clients and servers?
A:	If the time is not synchronized, a client may be confused about a file being old or new.

Chapter 34: HP-UX Automounter

1:	How is Automounter used for load balancing and fault tolerance?
A:	Automounter mounts file systems from the nearest of multiple NFS servers. In case a server is not available, it can mount a file system from another server.
2:	What is the difference between direct and indirect maps?
A:	A direct map has an explicit mount point. Directories in an indirect map are mounted within a reference directory.
3:	What rules apply to restarting the automount daemon after modifying different maps?
A:	If you make a change to a master map, you must restart the daemon. If you modify the options or server part in a direct map, you don't need to restart the automount daemon. If you modify a mount point, you have to restart the automount daemon. There is no need to restart the automount daemon if you make a change to an indirect map.

Chapter 35: Network Time Protocol

1:	What are three types of time sources?
A:	GPS satellites Radio broadcasts Internet time servers
2:	What is a stratum level?
A:	It is an indication of the accuracy of a time source. A level 1 time source is the most accurate and a level 15 time source is the least accurate.
3:	What is the use of a drift file?
A:	It is used to track any time drift in the local clock.

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