NETWORK ADMINISTRATOR
NETWORK ADMINISTRATION
DHCP (Dynamic Host Configuration Protocol) IPs: (Internet Protocols)
There are two versions in IP
1. Version 4.0
2. Version 6.0
IPs are of two types
Ø Static IPs
Ø Dynamic IPs
Static IP: static IPs are IPs what an admin assigns to the computer manually. Which are not changeable.
Dynamic IPs: Are the IPs, which are assigned by DHCP server, which are dynamic. i.e. not constant, changeable.
DHCP: useful for extremely larger networks where we want to centralize the I.P. management to reduce human errors.
Case2: Useful for smaller networks where there are no administrators or administrator may not be comfortable with assigning IPs.
ISP – Internet Service Provider
Usually ISPs implement DHCP servers
DHCP is a server which assigns IPs to the clients requested automatically from a range of IPs.
IP leasing process:
1. DHCP discover: The client machine when turned ON broad casts the network id, broad castes id, MAC address on Network for discovering DHCP server.
2. Offer: The DHCP server listening to the request made by the client offers a pool of IP addresses to the client machine.
3. Selection: The client machine on receiving the pool of IP address selects an IP and requests the DHCP server to offer that IP
4. Acknowledgement: The DHCP sends a conformation about the allotment of the IP assigned to the client as an acknowledgement.
5. IP lease: If the client machine is not restarted for 8 days, exactly after
4days the client machine requests the DHCP server to extend the IP lease duration, on listening to this the DHCP server adds 8 more days for existing 4 days =12 days
If the client machine is restarted again the DHCP lease process takes place and again the client gets an IP for 8 days.
DHCP requirements: DC or member server Static IP
AD
DNS (if it is win 2003)
Installing DHCP server (insert 2003 server CD) On DC
Start - setting – control panel – add\remove programs – add \rem windows components - Select n/w services – click on details
Select DHCP server – ok – next
Authorization: When we have multiple DHCP servers we can designate one of the DHCP servers as an authorized DHCP server.
Authorizing DHCP server: On DC
Start >p>admin tools
DHCP right click on the server
Click authorize
Refresh
Scope: Scope is a range of IP addresses from which the DHCP server assigns
IPs to the clients. Creating a Scope:
Open DHCP Server
Right click on server
New scope- scope name
Specify the range next
Specify if we want any exclusion
Lease duration
Next – DHCP options
Router – next – specify the domain name
Server name – client on resolve – add – next – WINS server – next - yes I want
– next – finish
Configuring a client machine to obtain IP from DHCP server
By default all the clients configured as obtain IP automatically
On client machine
Right click on my n/w places Properties – LAN properties TCP/IP double click
Ensure that “obtain an IP address automatically” is selected. Releasing an existing IP: (give up an IP)
Start >run>cmd>ipconfig /release
Obtaining a new IP
Start >run>cmd>ipconfig /renew
Super Scopes:
Group of scopes is called as super scope.
Note: when we have multiple scopes only one scope can be active in order to enable all the scopes we have to merge all the scopes with super scope.
Creating super scope Requires multiple scopes Create 2 scopes.
Right click on server
Say new super scope
Specify the super scope name Select 2 scopes by holding ctrl key Next – finish
Address Pool: gives the range of IP addresses we have specified
Address leases: specifies the client (names) and the IP addresses assigned Reservations: useful when we want to dedicate a particular IP to a particular system.
Ex: managerial systems, important clients.
To check the MAC address
Start-run-cmd>getmac
To check the MAC address of remote system
Start-run-cmd>getmac /s \\systemname
Implementing reservation
Open DHCP
Right click on reservations
New – reservation – give name - mention reservation name - MAC address of the remote machine – mention the IP address to be reserved
Close
Move on to client machine
Start - run – cmd – ipconfig /release – ipconfig - /renew
Scope options: Using scope options we can specify the other servers addresses available in the network. So that the DHCP server maintains information about all other servers and provides it to the client machines along with the I.P. addresses. For NT – 66servers addresses - for 2000-03 - 77
Server options: Useful when we have multiple scopes and provide information to all the scopes. Where as scope options are limited only to that scope.
Backing up DHCP:
Open DHCP - right click on DHCP – select backup
Select location where we want to save – ok
Restoring DHCP server: Uninstall DHCP server
Install DHCP server
Open DHCP Right click on it
Click on restore – specify the backed up path
We should notice our previous scopes.
Name Resolvers:
There are 2 types of name resolvers:
Ø WINS
Ø DNS
Resolver: It is a file which will contain the mapping information of the clients. Ex. System name and its IP address
WINS: (Windows Internet Naming Service) It is a service of Microsoft used basically on windows network to resolve NetBIOS names to IP address and IPs to NetBIOS names.
LMhosts: It is a static text file which contains NetBIOS to IP mapping information it was used instead of WINS.
WINS follow NetBIOS names: operating systems like NT, 95, workstation, 98 rely on WINS. Because these OS follow NetBIOS names
NetBIOS Names: Net bios names are the names assigned to network nodes. NetBIOS names are the names without extensions. They are called ‘flat names’.
2000 & 2003 also support WINS.
DNS (Domain Naming Service):
DNS resolves host names to IP addresses IP addresses to host names. Supports all type of OS. Ex. Windows, Linux, UNIX, Mac.., etc...
DNS: defines a hierarchical namespace where each level of the namespace is separated by a “.”
Resolver:
Resolving: It is a process of converting IPs to host names & host names to IPs. Computer that requests DNS resolution.
Issues queries that ask for specific types of mapping of computers and IP
addresses (records)
Query types determine behavior of DNS server receiving query.
Lookup types determine whether a name to IP mapping or an IP to name mapping is sought.
Query:
Query is a request to find an address of the DNS there are 2 types of queries.
Ø Recursive queries
Ø Iterative queries
Recursive Queries: When a client start a query, query is passed onto local DNS for resolution if a query cannot find the solution then the DNS on behalf of client forwards the query to another DNS, And to another DNS and so on until it finds the mapping information or an answer.
Iterative Query: Query raised by the client to the DNS. If the DNS cannot resolve it sends a negative response to the client, then the client has to contact another DNS and so on.
In this case the DNS is not forwarding the query but the client itself is contacting other DNS.
Zone: Zone is a subtree of DNS database. Zone contains the mapping information with the help of forward lookup zone & reverse look up zone.
Forward Look up zone: Contains host record, which contain host names to IP, address mapping information
Reverse Lookup zone: it contains mapping information about IPs to host. DNS requirements:
DC or member server
Static IP address
Installing DNS
Either on member server or on DC
Start - settings – control panel – add/remove programs – add/remove windows components – select networking services – details – check the box DNS – ok – next
Insert the CD - next
Creating a forward lookup zones: Start – p – admin tools – DNS
Right click on forward lookup zone
New zone – next – select primary – next – specify the zone name – zone file –
next –select allow both non secure & secure – next – finish
Records:
It is a database which contains information about the zone
There are a few types of records
Ø Host record (A record) used in FLZ
Ø PTR record (pointer) used in RLZ
Ø Alias record (nick name of a host record)
Ø MX record (used for mail server)
1. Creating a host record:
Right click on the zone you have created - new host – specify the servers address –and IP
Add host - ok - done
2. Creating an alias record: Right click on zone – new alias
Specify www. – Click on browse the host records – ok
Verification:
Start - run – cmd – ping www.Yahoo.com
Or ping sys1.yahoo.com
Creating a Reverse Lookup zone: Right click on the R-L zone
New zone – next - zone type - next – specify the IP address – zone file – next –
allow both – next – finish
Creating a PTR record
Right click on reverse lookup zone. New- pointer – specify IP
Browse host record – ok
Verification:
Start – run – cmd
Nslookup 192.168.1.17 - Reverse lookup zone
Nslookup www.yahoo.com Forward lookup zone.
DNS: DNS server can be configured as follows>
Ø Secondary
Ø Stub (feature of 2003)
Ø AD integrated
Ø Forwarders
Ø Root servers
Ø Caching only server
Ø Primary
Configuring a primary zone: On DC
Start - p – admin tools – DNS - create a zone & host record
Creating a secondary zone: On Member server
If DNS is not available install DNS first
Open DNS - right click on FLZ
New zone – next – specify the primary – DNS servers IP address –add – next –
finish
Zone Transfer
On DC
On Primary DNS
Open DNS – right click on zone
Properties
Zone transfer – check box allow zone
Select only to the following servers
Specify the secondary DNS servers IP address
Apply – ok
Primary Zone: Primary zones are created on the primary DNS servers. It is a read /write copy.
Secondary Zone: There are created on the second DNS server where it holds a read only copy of the zone.
Secondary zones provide fall tolerance and load balancing to the primary zone. Secondary zone is a back up for primary zone
Zone transfer:
Zone transfer is a process of transferring the zone from primary to secondary or secondary to primary. Zone transfers occur when there is a change or modification taken place on either of the zones.
AD integrated zones:
These are useful when we want to maintain zone information in the AD . zone is saved in the AD as a result when we back up AD we are also backing up zone information.
If it is a primary zone, zone is saved as a normal text file as a result we have to back p the zone separately, AD integrated zone is created when we install AD with a domain name.
Creating in AD integrated zone: On DC
Open DNS
Right click on FLZ New zone
Next - check the box store the zone
Next - specify zone name
Next – allow both – next – finish
Stub zone:
Stub zone is a newly added feature in WIN 2003 stub zone contains name server information or name server records and SOA records (Start of Authority)
Stub zones provide fault tolerance & load balancing besides providing the name server & SOA record information.
Stub zones are useful for resolving the query faster. Creating stub zones:
On DC
Create a primary zone with a host record ex: hp.com
On member server
Open DNS
Right click on FLZ New zone - next Select stub zone
Next – zone name ex.hp.com
Zone file – specify the primary DNS server’s address - next – finish
Resource Records (RR):
RRS are useful to provide the information about the zone. There are a few types of resource records.
Host a record Pointer record Alias record MX record AAAA record ATMA
HINFO etc…
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