Option 12 not working SG-350 (help needed)

[kevin-burrell]

Hi, I have a very basic question and not being a Cisco expert , I could use your help and advice as I cant seem toc rack this issue of my dhcp clients not setting option 12 and not storing/returning/reporting their hostname information when they are pinged. 

I'll start by saying, I am was not trained for this. I'm an engineer who likes to learn new things and decided this was something truly valuable to try.  Everything I've configured on my Sg-350 switch has been done by reading, watching videos and reading the forums. So please forgive me if I  but I can't seem to crack this last issue.

The DHCP clients dont seem to be setting a hostname, option 12, when they are allocated an ip address from one of the DHCP pools. This is causing my upstream DNS PI-Hole server to show IP addresses instead of the actual hostname. My solution so far is to manually configure known statically allocated clients on the switch and within the hostname of the pi-hole server, which works well, but continuing to do so, when i have family and guests join my wifi isn't workable.

A little about my network. I have configured my SG-350 as my home Vlan switch supporting 13 Vlans. My home network has over 100 devices, all placed in different Vlans to control access. This switch is connected downstream to a VPN router which grants WLAN access (192.168.0.1 using advanced router on that router to recognize each vlan ip range) and also downstream from a PI-Hole DNS server (192.168.0.2). This switch is then upstream to my mesh APs (3x for 5ghz) and 2 other AP (for 2.4 ghz). I then add clients to each VLAN using mac address groups. I have not yet configured or enabled RADIUS server (tbd). Each Vlan then manages their port using untagged configuration to allow access between the VLAN (i've often debated this, as I feel I've done something here, but if I change them to tagged, then all of a sudden the clients lose Internet access). The main internet router has been configured on an access port with the PI-Hole then connected directly to the WLAN router, while others ports on the switch have been configured as trunk. I have no idea if this is configuration is secure, but not being trained, it all works with 1 major problem, no DHCP hostname for my clients :(. I'm attaching the config file from the switch and hoping someone can point me in the right direction. I've read callouts to DHCP snooping, configuring DHCP relay, etc. Both the Main router and the PI-hole have DHCP capabilities, but the Switch is what handles DHCP for the VLANS and the clients.

Thank you for your help and guidance.

[kevin-burrell]

attaching network config file for reference

[KJK99]

To my knowledge, ping can report the hostname only if the DNS server has a PTR record for the IP address (reverse zone). Some DHCP servers can update DNS servers when they issue IP addresses, but I don’t believe the DHCP server on your switch is one of them. Well, at least the DHCP server on my CBS350 switch can’t do that. Also, DHCP clients may or may not add hostnames to their DHCP requests. I can tell from my own experience that many devices don’t do it or they just add some hardcoded names.

I see you have “client names” for your DHCP static hosts in your configuration file. I’m puzzled by those “client names” myself. They seem to do nothing. I can’t find any information on them in the manual or on-line help for my switch. According to one post on Internet, they are apparently related to BOOTP. I can’t tell. Maybe somebody else can explain that.

[kevin-burrell]

Thanks Kris, I appreciate it. 

hmmm,  so the client name for the static clients work, I can ping them via ip or hostname and they reply, the dynamically assigned ip addresses seem to be the problem. The other thing I noticed (see screenshot) is that the clients all have hostnames on the wifi client list (downstream from the switch) but not on the switch itself. This is after they've all gotten ip addresses allocated by the switch. 

appreciate all the guidance and help. For reference this is the switch I'm using : "Cisco SG350-10 10-Port Gigabit Managed Switch"

[KJK99]

When I wrote about ping returning hostnames, I thought about ping with the option -a that is available in Windows. nslookup with an ip address returns hostnames, too, if PTR records are set up.

I’m not sure where you want to see those hostnames of dynamic DHCP clients. My CBS350 switch does not show any hostnames in its address binding list and I don't expect them to be there. Although the CBS350 and the SG350 seem to be very similar, their WebUIs are different.

My APs, TP-Link EAP, show hostnames if dynamic DHCP clients send them. Again, not all them do that and some of them just send hardcoded names. My old ASUS routes made it possible to overwrite those hostnames, but my current APs do not. Fortunately, I can use an optional controller with those APs that shows an additional field which is called [sic] User Name. That field is populated either with hostnames, if available, or MAC addresses and can be overwritten. If that’s not possible in your Deco, I’m afraid nothing can be done. It is what it is ☹