What is purpose of host table?

johnifanx98

Lammel hints it's comparable to DNS. However, when I ping from a host, will router give a DNS response?

Ltat42a

It works like DNS, on a PC, it maps a name to an IP address. It's a simple text file (named "hosts"), yes, it will give you a DNS response. Go to a command prompt, ping www_yahoo_com(replace _ with a .)

TehToG

The host table is a legacy item. Back in the early days of arpanet there was no DNS. They designed a host table system whereby you could map a name to an IP to make it easier. The hosts table still exists today but it's use has more or less declined. Nowadays we have publicly trusted DNS servers to give us an IP for our dns names which is constantly updated and verified.

Further Reading....

mapletune

to be honest, this sounds more like something you'd need to know for Network+ not CCNA.

however, it's still good to know

johnifanx98

Ltat42a wrote: »

It works like DNS, on a PC, it maps a name to an IP address. It's a simple text file (named "hosts"), yes, it will give you a DNS response. Go to a command prompt, ping www_yahoo_com(replace _ with a .)

Hmmm... It does not look like a router will become name server with host table, or, the PT does not simulate it. I just set up a host in PT, and point its DNS to its local router. Add a host entry in the router. Ping this entry, and the router does not respond with DNS answer...

johnifanx98

mapletune wrote: »

to be honest, this sounds more like something you'd need to know for Network+ not CCNA.

however, it's still good to know

Exam topics:

Configure, verify and troubleshoot DHCP and DNS operation on a router (using CLI and SDM)

mapletune

yup, config dchp/dns using CLI and SDM on the router.

i don't think you need to go into a pc to look at it's host table.

but hey, i might be wrong

[edit]

unless you are talking about making a router THE domain server.

( most of the times, we just config and refer everyone to a public nameserver.)

anyway, for cisco CLI, to see name to ip mappings we can use:

show hosts

and to create static entries

ip host [name] (optional: port) [address] [address2] ... [address8] (other optional cmds)

TehToG

Knowing about the hosts table and using it in windows/linux/unix is part of troubleshooting.

MAC_Addy

johnifanx98 wrote: »

Exam topics: Configure, verify and troubleshoot DHCP and DNS operation on a router (using CLI and SDM)

I think you're reading too much into the exam topics. What book are you using?

johnifanx98

MAC_Addy wrote: »

I think you're reading too much into the exam topics. What book are you using?

I'm reading Lammle's ccna fast psass 2nd ed. Chapter 3 troubleshooting->name resolution->building a host table

phatrik

TehToG wrote: »

The host table is a legacy item.

The concept of a computer keeping a hosts file might be old, however it still has its uses even today. Here's a few: 1. I work for a hosting provider and often one of our tasks is to migrate a client's website and databases from their old provider to our data center. Once everything has been moved (website, databases) we will suggest to the client he tests the result of the migration before he updates DNS for the domain(s). This is usually done by the client overriding DNS servers for his domain by adding his domain name(s) as well as our IPs in his PC's host file. Of course, this is only useful when you're doing named-based virtual hosting. With only a single domain on a dedicated IP, you can always do http://NEW_IP. 2. This one perhaps more people will be able to relate to. I use a Firefox plugin called ABP (Ad Block Plus) which blocks out ads. Long story short: the author of the plugin maintains a list of domain names used for serving ads. That list is then added to your computer's hosts file, with each domain pointing to "127.0.0.1". As a result, the code on a website re-directing you to an ad server results in no ads being shown. 3. If you have somewhat of an extensive homelab (5+ PCs) it's always nice being able to connect to them using hostnames instead of remembering all of their individual IPs. i.e.: you can ssh to "gatekeeper" instead of having to ask yourself if gatekeeper is 192.168.100.2, .3, 4, etc... 4. After you've entered a registration key into an application, some applications will try to "call home" to verify the registration key. Need I say more?