Important Question and Answer – DHCP
Today we are discuss some important question and answer dynamic host configuration protocol purpose fourth part.
Q: 01:-If a single LAN has more than one subnet number, how can addresses be served on subnets other than the primary one?
A single LAN might have more than one subnet number applicable to the same set of ports (broadcast domain).Typically; one subnet is designated as primary, the other as secondary. A site may find it necessary to support addresses on more than one subnet number associated with a single interface. DHCP’s scheme for handling this is that the server has to be configured with the necessary information and has to support such as configuration & allocation. Here are four cases a server might have to handle:
A) Dynamic allocation supported on secondary subnet numbers on the LAN to which the server is attached.
B) Dynamic allocation supported on secondary subnet numbers on the LAN which is handled through a DHCP/BOOTP Relay. In this case, the DHCP/BOOTP Relay sends the server a gateway address associated with the primary subnet and the server must know what to do with it.
The other two cases are the same capability during manual allocation.It is possible that a particular server implementation can handle some of these cases, but not all of them. See section below listing the capabilities of some servers.
Q:02:- Can DHCP support remote access?
PPP has its own non- DHCP way in which communications servers can hand clients an IP address called IPCP (IP Control protocol) but doesn’t have the same flexibility as DHCP to acquire the IP addresses it gives out. This is sometimes called doing DHCP by proxy for the client. I know that Windows NT’s remote access support does this.
A feature of DHCP under development (DHCP inform)is a method by which a DHCP server can supply parameters to a client that already has an IP number. With this, a PPP client could get its IP number using IPCP, then get the rest of its parameters using this feature of DHCP.
SLIP has no standard way in which a server can hand a client an IP address, but many communications servers support non-standard ways of doing this that can be utilized by scripts, etc. Thus, like communications servers supporting PPP, such communications servers could also support the use of DHCP to acquire the IP addresses to give out.
The DHCP protocol is capable of allocating an IP address to a device without an IEEE-style MAC address, such as a computer attached through SLIP or PPP, but to do so, it makes use of a feature which may or may not be supported by the DHCP server: the ability of the server to use something other than the MAC address to identify the client. Communications servers that the acquire IP numbers for their clients via DHCP run into same roadblock in that they have just one MAC address, but need to acquire more than one IP address. One way such a communications server can get around the problem is through the use of a set of unique pseudo-MAC addresses for the purposes of its communications with the DHCP server. Another way (used by Shiva)is to use a different “client ID type “for your hardware address. Client ID type 1 means you’re using MAC addresses. However, client ID Type 0 means an ASCII string.